WASHINGTON—It happened again. Another candidate for office is struggling to reconcile misleading statements he made about his record in the military. This time, it is Rep. Mark Kirk, a Republican from Illinois running for the Senate, apologizing for misleading statements he made about, among other things, serving in the first Iraq war and in Kosovo.

“;I simply misremembered it wrong,”; he said, a remark that was blared across the front page of The Chicago Sun-Times on Friday. A few weeks ago, it was Richard Blumenthal, the Connecticut attorney general and Democratic candidate for Senate, trying to explain misstatements suggesting he had served in Vietnam.

This type of political behavior is hardly new. Over the years, a parade of politicians from both parties—John Kerry, Al Gore, Tom Harkin, George W. Bush, Bill Clinton and David Duke, to name a few—have had to account for what opponents portrayed as exaggerations or worse about their military service (or their attempts to avoid service altogether). Some of those candidates and many others have been called out for less-than-fully-truthful statements on countless other topics as well.

But the intensity of these latest skirmishes offers an insight into how the American political scene has changed. A common characteristic of politicians in search of votes—a propensity to puffery—has run head on into an aggressive new culture that subjects them to 24-hour flyspecking by opponents, bloggers, the mainstream media and regular citizens.

What is more, the rules of what is acceptable have grown murky since the days when Bruce F. Caputo, a Republican candidate for Senate from New York challenging Daniel Patrick Moynihan, was forced out after it was revealed that he had falsely claimed to have been drafted for Vietnam. (That information was leaked by a senior political operative to Sen. Moynihan, Tim Russert.)

The most pressing question for Blumenthal and Kirk is how much water they are taking on. As both are learning, analysts said, the issue in many cases is not so much whether they served in battle in Vietnam or Iraq, but the credibility and character of the candidate.

Kirk has admitted to a number of errors and discrepancies related to his military service. In the last week, Kirk acknowledged that his official House Web site incorrectly stated in 2005 that he served “;in Operation Iraqi Freedom”; when he was actually serving stateside. The problem was found that year and corrected to say that he had served “;during”; the invasion of Iraq.

Kirk has often said he served in Iraq—which his campaign clarified that he did for two months in 2000 in Operation Northern Watch, which enforced the no-fly zone above Iraq. He also served twice in Afghanistan.

“;Over the last generation, you've gone from people who were branded or identified with a party to races being much more about their character: Do voters trust them?”; said Chris Lehane, a Democratic consultant who advised Gore when he dealt with questions about exaggerating his service when he ran for president in 2000. “;That's one of the reasons that exaggerations have become a major part of a campaign. It is a way of telling whether you can trust something. It's something that opposition researchers, opponents, journalists can grab on to raise questions about.

“;You have far more scrutiny that in the past, no matter what anyone says about newspapers being on the demise,”; Lehane said.

Polls suggest Blumenthal has not been dragged down since the questions were first raised in an article in The New York Times. But Kirk has been forced this week to go on an apology tour to deal with challenges about the credibility of what he has claimed about his military record. Officials in both parties said the continuing questions could damage the prospects of Kirk, a five-term congressman and intelligence officer in the Naval Reserve, in his challenge against Alexi Giannoulias, a Democrat who had seemed vulnerable because of ties to the banking industry.

Candidates are prone to embellishing things in their past (from academic records to marital history), but war service has always been a particularly tempting area for exaggeration. Having a distinguished military career is a powerful drawing card, going back to George Washington.

“;More than half our presidential candidates have had military service of some kind,”; said Jeremy M. Teigen, a professor of political science at Ramapo College in New Jersey, who is writing a book on military credentials and political campaigns. “;And a not-so-small number of them have strategically emphasized that.”;

If the intensive media scrutiny of today is a warning to candidates to watch what claims they are making, it also leaves them vulnerable to the unearthing of any past dissembling, given how much easier it is now to hunt down old appearances and records and make them public. Nuances—like as the definition of the word “;serve”;—can be problematic, as Blumenthal has discovered.

“;The degree of difficulty of political exaggeration of any kind is directly correlated with the ease of research and the proliferation of sources,”; said Bob Kerrey, a Vietnam veteran and former senator from Nebraska who ran for president in 1992. “;It's so much easier to find something I once said when I was trying to convince people I was taller than Bill Clinton than it would be today.”;

“;In the old days—meaning the last time I campaigned in '94—if I had something hot on my opponent, if I had something that was really juicy, I would have go the bars where the journalists were and try to get them to print it,”; Kerrey said. “;Not anymore. I'd just have to post it on YouTube. It's quicker. And it's better for my liver.”;

Lehane, who is known for his talents at directing operations to gather unfavorable information about an opponent from their campaign appearances—in the vernacular, it is known as tracking—said chronicling what a candidate says and does is much easier now.

“;In 1992, when you wanted to track the candidate you had to send people out there with tape recorders, and try to get something you could use,”; he said. “;It was hard to get people close enough. It does seem that you used to get away with a lot more puffery than you can get away with now.”;

Emma Graves Fitzsimmons contributed reporting.