The Democrats have Sarah Silverman, mouthy comedienne, urging young Jewish voters in a video to "schlep it" to Florida to persuade their grandparents to vote for Sen. Barack Obama, the "goodest person I know."

The Republicans have Jackie Mason, mouthy comedian, who, in his own video, supports Sen. John McCain and calls Ms. Silverman -- while pictures of Barbra Streisand, Sen. John F. Kerry and other Democrats flash across the screen -- " a sick yenta," and asks, "What has Obama done? Nothing!"

All attempts at humor aside, the battle for the Jewish vote this year is no laughing matter.

In fact, it's gotten pretty tense out there. Democrats are complaining about Republican-sponsored "push" polls, rumor-mongering and attack ads that, they say, smear Mr. Obama.

Republicans, citing Mr. Obama's willingness to talk directly to leaders of Iran, are trying to sow doubts about Mr. Obama's support for Israel.

The stakes this year are huge -- especially in a battleground state like Pennsylvania, where Jewish voters make up about 4 percent of the electorate and, in a tight race, could tip the balance either way.

While Mr. Obama has been moving ahead in national polls, his support among Jews lags behind past Democratic candidates, at 57 percent to 30 percent according to one recent poll by the American Jewish Committee.

In 2004, Mr. Kerry's share of that vote was 75 percent, a number that has ranged from 64 to 90 percent since the days of Franklin D. Roosevelt -- with the notable exception of Jimmy Carter in 1980, whose share of Jewish support hit rock bottom at 45 percent.

Since that poll's release in mid-September, the Wall Street crisis may have boosted Mr. Obama's numbers among this group. But the question remains: Why is Mr. McCain getting more traction this year among less religiously conservative and secular Jewish voters who might ordinarily vote Democratic?

"He's independent-minded," said Sen. Joe Lieberman of Mr. McCain, a longtime friend and fellow foreign policy hawk. "He's a restless reformer with no patience for the partisan politics that pass for public service these days."

The Connecticut senator, a former Democrat re-elected as an Independent and the Democratic candidate for vice president eight years ago, spent a recent Friday touring synagogues and appearing at "Bagels with Joe" events in Philadelphia and its suburbs, stressing the Republican nominee's maverick image and citing Mr. McCain's break with the Bush administration on climate change and his support for closing Guantanamo Bay's detention center.

Today, Mr. Lieberman will introduce Mr. McCain at a tele-town hall with Jewish leaders from across the country.

Obama supporters say it's not just Mr. McCain's positives that are resonating with Jewish voters.

"I think a lot of it is due to the smear campaign that's out there," said Naftali Kaminski, 48, a physician and researcher at the University of Pittsburgh Medical Center. A staunch Obama supporter and a native of Israel who lives in Squirrel Hill, he has seen anti-Obama ads running on English-speaking Web sites of Israeli newspapers "trying to feed the suspicion that he is a Muslim or pro-Palestinian or anti-Israel."

"Besides being terrible distortions of the truth, these vile, hate-filled, Swift-Boating ads are everywhere in Ohio, Pennsylvania, and Florida," he frets.

Mr. Lieberman says he doesn't like those ads, either, "but I think ultimately people have enough common sense to separate out fact from fiction," he said in a recent telephone interview.

Besides stressing Mr. McCain's independence from Mr. Bush, Mr. Lieberman and other Republicans are hammering away at Mr. Obama and Iran -- repeatedly citing his statement that he'd meet with "appropriate" Iranian leaders after extensive diplomatic preparations. Republicans insist that means he would talk to Iran's president, Mahmoud Ahmadinejad, a Holocaust denier who has called for the annihilation of Israel. The Obama campaign says that's not the case.

"That was the last straw, but not the only straw," said Richard Heideman, a Washington, D.C. attorney. Mr. Heideman spoke on behalf of Mr. McCain at a candidates forum last month at the Jewish Community Center in Squirrel Hill, describing him as "the most experienced hand available to make judgments about life and death issues."

Mr. Heideman delivered a forceful brief for Mr. McCain to an audience of about 80 people -- most of whom appeared to be supporting Mr. Obama.

Opposing him was Gary Ackerman, an acerbic Democratic congressman from Long Island, who told the crowd that, on Iran and other issues, Republicans "are going around pushing our buttons. It's not as though Obama is going to sit down with [Iran President] Mahmoud Ahmadinejad and say, 'How about I give you all the Jews, serve them up on a silver platter.'

"Sen. Obama didn't say he would talk to Ahmadinejad. He said he supports discussions with Iran, and so do I. Didn't we talk to Krushchev or Anwar Sadat without preconditions?"

While these debates go on, both sides are vigorously working to target voters. The Obama campaign has set up Jewish "leadership committees" in various communities to hold training sessions with volunteers, who then go out and talk to their neighbors.

"Jewish voters go out and vote," said Clifford Levine, a Squirrel Hill attorney who has been active in those efforts, which include bringing in surrogates such as Anthony Lake, former national security adviser for President Bill Clinton, Mr. Lake appeared at Rodef Shalom Temple in Shadyside last month.

Mr. Levine nonetheless acknowledged that "this is election is closer than a lot of people think it should be. Older, traditional Democrats aren't quite there yet, even as their children are enthusiastically working for Obama."

"There are lots of older people there are going to work on folks living in the Squirrel Hill high-rises," added former radio talk show host Lynn Cullen, who is now campaigning for Mr. Obama. "One lady sitting next to me said, 'I'm targeting the bubbes.' "

Republicans have been relying on surrogates like Mr. Lieberman and the Washington, D.C.-based Republican Jewish Coalition, which is not affiliated with the McCain campaign but runs Republican advertising and organizing efforts.

"Up until now Democrats have been able to take the Jewish vote for granted but not this year," said Matt Brooks, executive director of the coalition, whose ads in Jewish newspapers have described Mr. Obama as "pro-Palestinian" and "anti-Israel." That ad campaign, along reports of telephone surveys suggesting that Mr. Obama had given money to terrorist groups, has enraged Democrats.

"Do these guys have any shame?" asked Ira Forman, executive director of the National Jewish Democratic Council, who held a news conference last month claiming that the RJC was behind the surveys.

"I test messages," he said. "The Republican Jewish Coalition is testing lies."

"I can assure you we never asked any questions about Obama donating money to the PLO," Mr. Brooks said, noting that his group's survey was not a "push poll" -- short phone calls to thousands of voters which masquerade as surveys but are really designed to pass along negative messages.

Rather, the coalition's most recent poll of 750 voters -- in Florida, Michigan, New Jersey, Ohio and Pennsylvania -- featured 82 questions on a wide range of issues, about 10 percent of them involving questions designed to test negative messages about Mr. Obama.

Deb Minden, a Squirrel Hill psychologist, said she received a call a few weeks ago from pollsters "who asked me how I would feel if I knew Barack Obama was giving money to Hamas or spoke to Hezbollah. It actually sounded like a real poll at the beginning. They wanted names, demographics, were asking generic questions about the candidates," she said.

But when the questions turned to Mr. Obama's associations with terrorists, she felt disgusted.

"It was just garbage," she said. "I hate to think that people think you can scare somebody off and that Jews are only single-issue voters and the Jewish community is so flat in its outlook."

Nonetheless, the single issue of Israel remains paramount for many, and Mr. Obama's surrogates have been working hard to dispel the notion that Mr. Obama is somehow weaker on the issue than Mr. McCain.

"What I've been asking people, when I speak at synagogues, is to ask themselves is not just which candidate would be stronger friend of Israel, but which America would be," said Mr. Lake. "An America that is coming together, that is more unified, that puts aside divisive tactics would be a stronger friend to the Jewish state. That, along with direct talks with Iran to back off its nuclear program, and negotiations with the Syrians would result in our having a stronger standing in the Middle East."

There's also the complex, delicate issue of racial bias, says Jessica Emerson-Fleming, founder of Jewish Grandchildren for Obama, which, like Sarah Silverman's TheGreatSchlep.com, is trying to mobilize younger voters to persuade older relatives to vote for Mr. Obama.

Those younger voters are having to talk about race much more than they expected, she added, a task requiring some diplomatic skill.

"You can't have grandchildren calling their grandparents racist. On the other hand, we think it's very important to call out racism, especially when it's an undercurrent. A lot of people don't realize how what they're saying sounds until they're called out on it."

Even McCain supporters say they're uncomfortable with the ads and e-mails that have been circulating.

They're "unfortunate and blatantly not true," said Daniel Berkowitz, a former Department of Defense employee who is opening a kosher bakery in Squirrel Hill, "and that's a shame because there is so much we can talk about on the issues that support Mr. McCain's candidacy."

Given their relatively small numbers, though, it's not clear if Jewish voters like Mr. Berkowitz will engender a big enough shift toward the Republican to make a difference -- even as emotions on both sides are running high.

"My entire street is Obama," said Cheryl Moore, 43, of Squirrel Hill, and a staunch McCain supporter. Her congregation, Rodef Shalom, "is about 90-10 for Obama, and that's fine, it doesn't bother me at all. This is America.

"But I had a sign out for McCain and it was taken down. What's hard for me is the assumption that there is something wrong with my character and intelligence if I'm voting for McCain. I really do feel a little isolated."

Dr. Kaminski said he's never seen such interest in politics in his dozen years in the U.S.

"You never knew what the next person thought. Now, you go to the 61C Cafe in the morning, and you know what everyone thinks."