Connecticut Attorney General Richard Blumenthal has issued a formal apology for inaccurately portraying his military service during the Vietnam War -- nearly a week after the Democratic candidate for Senate was first confronted with allegations of misleading voters.

Blumenthal said in an e-mail to The Hartford Courant late Sunday that he has taken "responsibility" for his statements.

"I have made mistakes and I am sorry. I truly regret offending anyone," he said. "I will always champion the cause of Connecticut's and our nation's veterans."

Blumenthal is under fire for saying, on several occasions, that he served in the Vietnam War when he was a Marine reservist who never left U.S. soil. He held a press conference last Tuesday to express regret for the claims. But he did not formally apologize at the time and claimed that public misstatements about his Vietnam service, first published in The New York Times, were unintentional and rare.

Since the Times report was published, local newspapers have unearthed more statements showing Blumenthal claiming he served "in" the Vietnam War, as opposed to during it.

Republican candidate Linda McMahon, former CEO of World Wrestling Entertainment, called Blumenthal's apology on Sunday "hollow."

"The statement Dick Blumenthal released in the dead of night yesterday cannot be construed as an apology because it ignores what is at the heart of the controversy surrounding him: false and misleading statements designed to deceive," she said in a written statement.

Still, the top official in charge of electing Democrats said Sunday the controversy won't mar his reputation.

Democratic National Committee Chairman Tim Kaine said Sunday that Blumental was wrong to say that he had served in the Vietnam War, but that he's a known and reliable official for Connecticut voters.

"The interesting thing about Connecticut ... pretty intimate state. People tend to know their political leaders. And Attorney General Blumenthal has served for a lengthy period of time, got a very strong track record on military and veterans issues, for example," Kaine told "Fox News Sunday."

"What the voters of Connecticut will wrestle with as the attorney general, somebody that they've known -- he's been in office a long time. I think they have a sense of who he is," Kaine added.

But Republican National Committee Chairman Michael Steele said Blumenthal, who got five deferments to avoid going to war, can't possibly have an excuse for claiming he was in Vietnam when he wasn't.

"The statements were knowingly wrong. I mean, you know what you did and when you did it and how you did it," Steele said. "He knowingly misrepresented what he did. And that's a serious concern for a lot of voters out there."

Video and newspaper articles showed him several times suggesting he had served in country during the war, including in a 2009 Connecticut Post article in which he was quoted saying, "When we returned from Vietnam, I remember the taunts, the verbal and even physical abuse we encountered."

The attorney general did win the endorsement of the state Democratic Party over the weekend. World Wrestling Entertainment CEO Linda McMahon, who took credit for finding the misstatements, won GOP backing. Both the Democratic and Republican primaries are in August.

Kaine said he thought Blumenthal had occasionally gotten away from himself in the moment of speech-making but had corrected the record. He said veterans had not been misled into thinking he had served in Vietnam with them, and voters will "weigh this in the grand scheme of things" and find his record is reliable.

But Steele said Blumenthal holding a press conference to clarify his remarks won't stop people from questioning his credibility.

"You can't say, well, you know, on the one instance, I lied to you, but on the other, since I made up for it by explaining why I lied to you. It doesn't make sense to the American people," he said.

Sen. John Cornyn, R-Texas, head of the National Republican Senatorial Committee, added that Blumenthal damaged his reputation as trustworthy not only by misrepresenting his record but by then trying to patch up the situation.

"The only worse thing, I think, is then coming on and saying, 'Oh, I misspoke,' after you've been caught red-handed," Cornyn said on NBC's "Meet the Press." "It's as if he shot himself in one foot, then reloaded and shot himself in the other."