For tens of thousands of new Democrats, the April 22 primary election comes down to just two options: Hillary Rodham Clinton or Barack Obama.

But they have many more. How about John Cordisco or Robert McCord? Dennis Morrison-Wesley or Jennifer Mann?

All four will be on the statewide Democratic ballot -- for Pennsylvania treasurer. And there are dozens of contested congressional and state legislative races.

Thanks to the excitement surrounding the presidential election, the number of registered Democrats in the state has surged to 4,198,774, according to figures released yesterday by the Pennsylvania Department of State.

That's 315,401 more than last November's registration.

Many local candidates are scrambling to reach out to those new voters, who could be the key to victory in races they don't even know about.

The typical winning strategy in low-turnout primary races usually requires the backing of the local party machinery, which often serves as a boost for incumbents.

This year, however, many voters are entering the political process because of the "change" message coming from the presidential campaigns. It's unlikely that they'll strictly follow, or even be aware of, the advice of party bosses.

"By and large, the incumbents probably need to be somewhat concerned, especially if there are only one or two candidates opposing them," said Gerald Shuster, a professor of communications at the University of Pittsburgh.

That could pose a problem for state Rep. Joseph Preston Jr., who in 2006 came within 93 votes of losing the seat he has held for more than two decades.

Now he faces three challengers: Lucille Prater-Holliday, Todd E. Koger and William D. Anderson.

"We are the new voters," said Mr. Anderson, 35, a Homewood body shop owner and head of the Pennsylvania Coalition of Young Democrats. "All the math and all the calculations are being thrown to the wayside."

He finished third in the 2006 race.

The district, which stretches from Pittsburgh's eastern neighborhoods into Wilkinsburg, now has 37,218 registered Democrats, an increase of 1,667 from a year ago, according to the Allegheny County Elections Division.

Mr. Preston, of East Liberty, last week said he was just starting to analyze those numbers. Some are voters who reregistered after having been purged from the county list because they skipped too many elections. Others registered for the first time.

Mr. Preston, who came to office in 1983, says he can appeal to new voters despite his lengthy tenure in Harrisburg.

"I don't take anything for granted," he said. "I always continuously evolve."

He cites his decision to become a proponent of mixed-income housing developments. He also no longer supports property taxes, calling them "redundant" and an obstacle to home ownership, especially among young people.

He is backing Mr. Obama, the candidate who has made change the central theme of his campaign from the beginning. Mr. Preston estimates that Mr. Obama has the support of as many as 70 percent of the voters in his district.

Mr. Preston will be on the ballot next week as an Obama delegate.

Mr. Anderson doubts that Mr. Preston can capture the Illinois senator's message.

"Since I was 9 years old I haven't seen any change," he said of his neighborhood. "None of the candidates can explain to me what they've done."

Another incumbent, state Rep. Jake Wheatley, also is embracing Mr. Obama's candidacy.

His district, which covers more than a dozen city neighborhoods, including the Hill District and the South Side, has 2,361 new Democrats, according to Mr. Wheatley's campaign. The candidate plans an outreach effort of mailings and door-to-door canvassing.

"I believe the new voters are just interested in supporting people who can make government work," he said. "If you can talk to them about their issues and what's important to them, you'll be fine."

Deidra L. Washington left her job as site manager for the Pittsburgh Housing Authority to run against Mr. Wheatley, who was first elected in 2002. She thinks voters are looking for a new voice in Harrisburg.

"A lot of them are coming out for change," she said. "They were disenfranchised by the old politics."

Mr. McCord, a financial analyst from Montgomery County, has attended both Obama and Clinton rallies to walk among the huge crowds and pitch his candidacy to supporters of each candidate.

"They're often surprised there is an office called 'treasurer,'" he said.

He said he's had some success drawing connections between the powers of the office and the issues that interest new voters. For instance, he promotes the treasurer's ability to make responsible investments in energy mutual funds that are environmentally friendly.

Mr. Cordisco, chairman of the Democratic Party in Bucks County, said he, too, is trying to "piggyback" on the Obama and Clinton bandwagons.

Last month, his volunteers handed out thousands of leaflets among the throngs that greeted Mr. Obama on the lawn in front of Penn State University's Old Main.

He is also following the script of any successful statewide campaign, covering more than 11,000 miles since January and visiting more than 50 of Pennsylvania's 67 counties.

Most candidates are unwilling to alienate a significant slice of the electorate by getting behind either Mr. Obama or Mrs. Clinton. Instead, they praise both.

"These are exciting times. I think we have two good candidates," Mr. Cordisco said. "I don't want to impose my position on someone."

Mr. McCord expressed "pride" in the party's two presidential hopefuls.

In Pennsylvania's 18th Congressional District, none of the three Democratic candidates -- Beth Hafer, Steve O'Donnell and Brien Wall -- will announce a public preference.

Ms. Hafer, a former teacher and vice president of Hafer & Associates, thinks she is in the best position to capitalize on the historic race for the White House. If she wins her party nomination and goes on to defeat Rep. Tim Murphy, R-Upper St. Clair, she would be the first female Democrat to represent Western Pennsylvania in Congress.

At age 35, she also thinks she can appeal to the younger voters who are likely to turn out in large numbers next week.

She also has another advantage: the same last name as her mother, Barbara Hafer, a former Allegheny County commissioner, state treasurer and state auditor general.

Mr. O'Donnell, 62, a Monroeville businessman, said he has to work "three times harder" to connect with voters.

He does have his own advantages. He has been able to raise more money than Ms. Hafer, in part because of his personal wealth. He also has the endorsement of the Allegheny County Democratic Committee. Ward and municipal leaders for the committee will hand out slate cards at the polls to inform new voters about the endorsed candidates.

Mr. Wall thinks he can appeal to Republicans who became Democrats to vote in the primary because of his conservative social views, such as his opposition of abortion.