US Representative Walter Jones, a conservative Republican, does not hide his anger when he says bad information led him to vote for the Iraq war.
"If I had known then what I know today, I wouldn't have voted for that resolution. Absolutely not," he said Thursday in an interview.
His comments reflect concerns of other Republican lawmakers in Congress, and polls show a lingering debate over the reasons for going to war have hurt the administration even as the Iraq operation shows signs of success.
A day earlier, during House Armed Services Committee testimony on the Iraq war, Jones demanded an apology from the administration of President George W. Bush.
"To me, there should be somebody that is large enough to say, 'We made a mistake'," Jones said, almost in tears with frustration. He said he and other lawmakers want to ensure they are never again asked to authorize a war with bad information.
Jones felt so bad he decided to write personal letters of condolence to the families of each of the more than 1,600 US soldiers killed.
He has so far sent more than 900.
"My heart aches every time I sign these letters and I want them to look right," he said.
The funeral of a Marine sergeant, among the first US casualties of the war, along with Jones's Christian faith, inspired him to write the letters.
"Spiritually, it's something that I felt I had to do," he said.
Bush has recently won back some political ground in the US-led effort to remove Iraqi leader Saddam Hussein and build a democratic society there.
Iraq's January 30 elections were widely judged as a success, and a new Iraqi government has begun to take shape with the election of Kurdish leader Jalal Talabani as the largely ceremonial president and Muslim Shiite Ibrahim Jaafari as prime minister.
US-trained Iraqi security forces are now taking a larger share of the fight against insurgents, and Pentagon officials talk about withdrawing some of the 145,000 US troops in Iraq.
The number of US casualties in March, 36 killed and 166 wounded, are at their lowest levels in a year, according to the Brookings Institution, a Washington think-tank.
The administration has seen its main justification for war evaporate, however, most recently when a presidential commission found that US intelligence agencies were "dead wrong" in saying Iraq had illegal weapons.
That failure doesn't play well in Jones's rural, conservative North Carolina district, he said. The state went strongly for Bush last year and includes the giant Camp Lejeune Marine base, a major source of troops for Iraq.
It's a constituency Bush, also a Republican, can ill afford to lose as he tries to keep his options open for dealing with the nuclear ambitions of Iran and North Korea amid Democratic opposition to some of his policies.
The weapons issue has eroded support for Bush on Iraq nationwide, according to the Pew Research Center for the People and the Press.
The centre’s latest poll found that Americans were more dissatisfied with the reasons for going to war, and with Bush for taking the nation into the conflict, even as they continue to support the effort.
Some 54 percent said things were going very well or fairly well in Iraq, up from 48 percent in a similar poll in January. But the share of those who thought the war was the wrong decision rose from 44 percent to 47 percent, and those who thought it was the right decision declined from 51 percent to 47 percent.
And just 40 percent approved of Bush's job performance on Iraq, down from 45 percent in January.
The poll was conducted February 16-21 among 1,502 adults, with a margin of error of three percentage points.
"It seems as though they make a clear distinction in how the US government got in and what they should do now," said Carroll Doherty, an opinion expert for Pew.