A Democratic senator on Thursday said that CIA Director George Tenet (search) told a Senate panel that White House officials insisted on including a claim in President Bush's January State of the Union address about attempted uranium purchases by Iraq.

The information in the speech turned out to be based on faulty intelligence.

Sen. Richard Durbin, D-Ill., said Tenet refused to give the individuals' names, but he is certain the fault lies at the White House.

"All roads still lead back to 1600 Pennsylvania Avenue," Durbin said in a television interview Thursday. "The question is, who in the White House was so determined to put information in the State of the Union which had been discounted so dramatically by American intelligence sources?"

The White House responded that Durbin's claims are "nonsense" and not surprising coming from a lawmaker who voted against authorizing the Iraq war.

On Wednesday, Tenet answered Senate Select Intelligence Committee members' questions about how hard he tried to wave Bush off the intelligence about Iraq's nuclear weapons pursuit and whether he felt pressure to help the president make the case against Iraq.

The director of Central Intelligence repeated his statement that he bears responsibility for allowing the claim to appear in the president's annual speech to the nation, even though aides say he made it clear he was skeptical about the intelligence.

After Wednesday's four-hour, closed-door hearing, Intelligence Committee Chairman Pat Roberts, R-Kan., described Tenet as "very contrite. He was very candid, very forthcoming. He accepted full responsibility."

But Sen. Ron Wyden, D-Ore., said that Tenet was taking too much of the blame.

"I believe that there was if not a battle royal between the CIA staff and the White House staff, certainly some back and forth," he said. "I believe that in this case, the White House political staff was looking at every rock, every nook and cranny to make their case and I believe the political staff prevailed."

Roberts said it was clear "there were mistakes made up and down the chain." He said the hearing reaffirmed his belief that "the handling of this was sloppy."

Roberts also said he expected to hold open hearings on the Iraq intelligence, probably in September.

Democratic critics have been asking sharper and sharper questions about the president's January State of the Union (search) address in which Bush said British intelligence had reported Iraq was trying to buy uranium in Africa.

A senior law enforcement official said the FBI has opened an investigation into the documents. The focus is on who could benefit from putting false information into U.S. hands.

The official said the FBI is not investigating the U.S. government, but is looking at a variety of foreign entities, from other governments to anti-Saddam Hussein groups that favored a U.S. invasion.

The FBI sent a letter last week to Sen. Jay Rockefeller, D-W.Va., saying it had opened the probe. Rockefeller had called for such an investigation last spring.

Before the closed hearing, North Carolina Sen. John Edwards (search), a presidential contender, said he has serious questions about Bush's credibility.

"First, I want to find out how many people in the White House knew, before the president gave the speech, that there were serious questions about the truthfulness of the statement, and the reliability of it," Edwards said.

Edwards also went after the president over what is happening now in Iraq, where, he said, the lives of young American men and women are at risk.

"One of the reasons their lives are at risk is because the administration did such a poor job of planning for the aftermath. This is a critical issue. The president made an enormous mistake by not planning properly," he said.

Democrats say the question comes down to whether the intelligence supported the urgency of the threat the White House portrayed and whether Bush ignored caveats and qualifiers that may have made the case for war less compelling.

But Republican Sen. Christopher "Kit" Bond (search), R-Mo., said that intelligence is supposed to be non-partisan and not second-guessed.

"[The intelligence] ultimately proved successful for winning the war in Iraq, and number two, pointing out the fact of weapons of mass destruction, had we not intervened, might have in the future resulted in nuclear weapons. So this is regrettably a politicization of intelligence," Bond told Fox News.

That so-called politicization continued Thursday. Massachusetts Sen. John Kerry, a Democratic presidential candidate, released a statement saying Durbin's account of the testimony revealed disturbing events at the White House.

"It's deeply troubling, but not altogether surprising, to learn that there may have been direct political pressure exerted on the CIA to exaggerate nuclear claims in the president's State of the Union address. This is just more evidence that, as I said yesterday, President Bush must support a full and independent investigation so that the American people know the full truth about what happened."

On Wednesday, Kerry took broad shots at Bush, starting with what he called a "lack of credibility" in the president's arguments about going to war in Iraq.

"Americans should be able to trust that what the president tells them is true — especially when it comes to the life and death decisions of war," Kerry said.

Saying it is time for the truth, Kerry clearly accused the president of being dishonest in some way about prewar intelligence. He also accused the president of dropping the ball on homeland security by underfunding police and firefighters —- what Kerry called "a preparedness gap."

"It's time we were told the truth about America's safety. It's time we had a president who will truly make America more secure," he said, adding that Americans have a right to ask whether they are safer today than they were in the days after the Sept. 11, 2001, terror attacks.

White House spokesman Scott McClellan had a ready answer.

"I recognize there are a number of Democratic candidates trying to gain an advantage in an election. But the bottom line is, America is safer, more secure, and better prepared than we were on Sept. 11, 2001," McClellan said.

McClellan also returned fire against Kerry, noting that he had a different view of Saddam's weapons and threats when President Clinton was in office.

McClellan noted that in 1998, Kerry called Saddam's weapons a "threat to the stability of the Middle East" and a threat with a potential for terrorist activities.

Quoting Kerry, McClellan said, "If we don't face this today, we will face it at some point down the road."

He added that critics are trying to rewrite history by questioning the idea that Iraq didn't pose a threat, and he said that Democrats are trying to benefit politically by criticizing a war many of them supported.

Fox News' Jim Angle, Wendell Goler and The Associated Press contributed to this report.