The trouble with being a member of Congress, John Kerry (search) once lamented, is that you can't vote "yes, but" or "no, but."

Kerry has cast thousands of votes in his nearly 20 years as a senator from Massachusetts, and they place him squarely in the Democratic Party mainstream. He's given a lot of speeches over the years, too, and those words sometimes have suggested a more nuanced world view.

"He votes with his party even though his critiques have sometimes gone against the grain of the party," says Elaine Kamarck, a public policy professor at Harvard University who was an adviser to Al Gore in the 2000 campaign.

As the front-running Democratic presidential candidate, Kerry is finding both his votes and words coming under increasingly intense scrutiny, and he spends a considerable amount of time explaining his thinking.

On one hand, Democratic rival Howard Dean (search) has repeatedly criticized Kerry's 2002 vote authorizing the United States to go to war against Iraq, painting him as just another Washington insider. On the other, Republican Party Chairman Ed Gillespie (search) this week cited Kerry's 1991 vote against military action in the Persian Gulf as one in a string of votes he said suggest the senator is weak on national defense.

The rationale for such votes — not just for Kerry, but for any candidate with a congressional record — often can get lost in a campaign of glib sound bites and quick retorts.

Nearly a year ago, Kerry spoke of the challenge.

"This is the difficulty in any vote: You can vote 'no, but' and there are a whole lot of qualifiers, or you can vote 'Yes, but,' and there a lot of qualifiers sometimes," he said. "The way people read the votes, they don't see any of the qualifiers."

Whatever the qualifiers, Kerry has consistently voted his party's line, as reflected in ratings issued by various interest groups: a lifetime score of 5 from the American Conservative Union, a rating of 85 for 2001-2002 from the liberal People for the American Way.

The value of such ratings, though, is limited. For example, the scores for Sen. Joe Lieberman of Connecticut, the most centrist of the Democratic presidential hopefuls, aren't much different from Kerry's. Lieberman's rating from People for the American Way was identical to Kerry's — 85.

Darrell West, a political science professor at Brown University, describes Kerry as falling "at the pragmatic end of liberalism."

"He's somebody who has carved out his own path, and occasionally questioned doctrinaire positions, so although he is a liberal, he won't be quite as easy to pigeonhole as Republicans are claiming," West said.

Dean has stepped up his criticism of Kerry's record in recent days, on Friday saying the senator hadn't accomplished much and that the presidential nominee should be "a doer, not a talker."

Kerry's response is that effectiveness in Congress isn't measured by the number of laws that carry one's name and that he's helped pass important laws providing benefits such as family medical leave, mental health care and children's health care.

The senator also is increasingly the target of Republican fire now that he has emerged as the Democratic front-runner. The GOP's Gillespie, besides labeling Kerry soft on defense, has cast him as an Eastern liberal out of sync with voters on economic and social issues.

Kerry, for his part, says he's happy to campaign on his Senate record, confident his background as a Vietnam war hero will help deflect any questions about his commitment to national security. He also can point to votes that show a centrist bent — in favor of welfare reform, trade legislation and the Gramm-Rudman deficit-reduction law, for example.

His speeches, too, sometimes stray from Democratic dogma. In 1992, for example, he gave a speech saying affirmative action, which he supports, has had costs as well as benefits. "There exists a reality of reverse discrimination that actually engenders racism," he said.

Taking a hard look at public schools in a 1998 speech, he decried the "political timidity and powerful interest groups" that were keeping the nation from meaningful education reforms that would improve substandard schools.

But now Lieberman's campaign accuses Kerry, and another Democratic presidential rival, Sen. John Edwards of North Carolina, of backing away from President Bush's 2001 education reform package in deference to complaints from the education establishment. Kerry voted for the package, known as the No Child Left Behind Act, but now wants to revise it and complains that Bush has failed to back up the law with enough money to help schools raise academic standards.

Kerry has built his Senate reputation more on pursuing investigations than crafting legislation. For example, he led a subcommittee probe into the Bank of Credit & Commerce International scandal and subsequently wrote a book that helped document how international criminal and terrorist networks work together.

Ed Kilgore, policy director for the centrist Democratic Leadership Council, said that Kerry over the years has shown himself to be a thoughtful legislator who sometimes "has pushed his party to a little bit of fresh thinking."