HARRISBURG -- Even the most hard-core opponent of the Legislature's 16 percent pay raise admits the odds are long against it being overturned in court.

But it may just be a gamble worth taking, three longtime governmental observers said yesterday.

A citizens lobby called Common Cause/Pennsylvania is considering a wide range of options, including a lawsuit and two pieces of legislation, to fight the pay raise that state legislators approved for themselves in the early-morning hours of July 7.

"We are exploring all our options, including the litigation option,'' said Executive Director Barry Kauffman.

Despite unsuccessful lawsuits against previous raises, one in 1986 by a group called the Consumer Party and another in 1995 by Harrisburg activist Gene Stilp, Duquesne University law school Professor Bruce Ledewitz believes the Legislature's action this time clearly violated the state constitution, which prohibits a legislator from getting a raise during his or her term.

To avoid the constitutional prohibition, legislators are calling their raises, which began taking effect on Monday, "unvouchered expenses'' rather than actual raises.

Ledewitz said that's nonsense.

"You can call it whatever you want -- you can call it an unvouchered expense or you can call it tomato soup -- but it's still a pay raise,'' he said.

"This action flies in the face of the constitution, in my opinion,'' he said. "I am ashamed of them for violating the law. Why couldn't they wait?'' to take the raises when their new terms begin in January 2007, he asked.

Jeff Coleman, a former Republican legislator from Armstrong County who is vice president of the Commonwealth Foundation, a conservative think tank, also criticized the pay raise.

He called the issue "the perfect storm'' in terms of angering almost all segments of the public.

"The pay raise crosses philosophical lines, upsetting groups both on the right and the left. Everything is on the table,'' he said, including a lawsuit.

Defeating incumbent legislators in Pennsylvania has been almost impossible. But Coleman, who defeated an 11-year incumbent in 2000, said voters are so angry over the raises that 2006 may be different.

"If there ever was a year when there could be a dramatic shift in the General Assembly in favor of reform, next year would be the year,'' he said.

The pay raise was approved without comment or public hearings by the House and Senate at about 2 a.m. July 7. Of the 203 House members and 50 senators, 158 have elected to receive the heftier checks, which they began getting on Monday.

Stilp, who was unsuccessful in suing in 1995, is trying again. He filed papers in Commonwealth Court on Monday.

Kauffman said he's talking to lawyers and other public interest groups about filing a suit of his own. But he cautioned that going to court would almost certainly become expensive and time-consuming, as legislators who like their higher pay file legal challenges and seek to drag out the proceedings.

Two legislative options also are under study. One measure would forbid incumbent lawmakers from taking additional compensation in the form of monthly "unvouchered expenses.''

Kauffman said Common Cause also may support a bill being drafted by Rep. Will Gabig, R-Carlisle, that would make it illegal for legislators to receive unvouchered expenses. Kauffman said the constitution mentions only two forms of compensation for legislators -- salary and gasoline reimbursement for travel, and says nothing about unvouchered expenses.

Critics such as Ledewitz complain that the use of the device of unvouchered expenses is simply a subterfuge to get around a constitutional prohibition on a lawmaker taking a pay raise during his or her term.

Ledewitz, ironically, isn't against a pay raise, which applies to more than 1,000 judges and several dozen members of Gov. Ed Rendell's Cabinet as well as the 253 legislators.

"I think a pay raise is justified for all three branches of government, but you're supposed to give legislators a raise after their term is over, not in the middle of a term,'' he said.

Legislators' new terms won't begin until after they are elected or re-elected in November 2006 and lawmakers who support the pay raise are clearly hoping that public anger will cool by then.

Kauffman said he might also pursue a bill to make it a criminal offense for a legislative leader to retaliate against a rank-and-file lawmaker for voting his conscience.

That appears to be what House Democratic leader H. William DeWeese did last week in removing from subcommittee jobs 15 legislators who voted no on the pay raise. Even Gov. Ed Rendell, who signed the pay raise bill, said it appeared that those who voted no were being punished for voting as their consciences dictated.

Kauffman said he sees problems with the pay raise bill, called House Bill 1521. It was changed from a measure just for executive branch raises into raises for all three branches, but didn't receive the requisite three days of hearings in its altered form.

Legislators also didn't do a "fiscal note'' on the bill, he said, meaning calculating the cost of raises for over 1,300 officials. The cost later was estimated at about $16 million this year.

The law may also violate the theory of an independent judiciary, Kauffman said. That's because a "nonseverability clause'' was inserted. That means that if a court knocks out raises for legislators, it also knocks out raises for judges and Rendell Cabinet members.

Kauffman is getting help and advice from other nonprofit public interest groups, including the Commonwealth Foundation and a 4-month-old group called Pennsylvania Club for Growth.