Bush needs to tell Americans that the nation faces "a long, hard slog" in Iraq, Senator John McCain, an Arizona Republican, said on NBC's "Meet the Press" on Sunday.
On the same day, Senator Chuck Hagel, a Nebraska Republican, said the White House is "disconnected from reality" in its optimism over the war.
McCain, a member of the Senate Armed Services Committee, said: "Too often we've been told and the American people have been told that we're at a turning point.
"What the American people should have been told and should be told ... [is that] it's long; it's hard; it's tough. It's going to be at least a couple more years."
Hagel, a member of the Foreign Relations Committee was quoted by US News and World Report as saying the administration's Iraq policy is failing.
"Things aren't getting better; they're getting worse. The White House is completely disconnected from reality. It's like they're just making it up as they go along. The reality is that we're losing in Iraq."
The two Senators' remarks came as the Bush administration makes a push to counter growing US public impatience with the Iraq war, and to resist demands by some lawmakers to set a date for the withdrawal of US forces.
"Things aren't getting better; they're getting worse. The White House is completely disconnected from reality. It's like they're just making it up as they go along. The reality is that we're losing in Iraq"
Senator Chuck Hagel
US public polls show the Iraq war is losing support and hurting Bush's popularity.
While US Vice-President Dick Cheney has asserted that anti-US violence is in its "last throes," a bombing in Baghdad on Sunday that killed at least 23 people underscored the unabated bloodshed.
Iraq's al-Qaida group claimed responsibility for the bombing and said US forces are doomed to failure.
Although there are some hopeful signs in Iraq, Cheney's characterisation is inaccurate, McCain said.
"I don't think Americans believe that we should cut and run out of Iraq by any stretch of the imagination," he said. "But I think they also would like to be told, in reality, what's going on."
More than 1722 US soldiers have
been killed in Iraq
Democratic Senator Christopher Dodd of Connecticut, a member of the Foreign Relations Committee, said on "This Week" on ABC: "It's important the administration quit trying to pretend everything is going very well here. It's not."
CIA Director Porter Goss, however, said Cheney's assessment is not too far off-mark.
"I think they're not quite in the last throes, but I think they are very close to it," Goss told Time magazine. The emergence of an Iraqi government shows the fighters are "unwanted", he said.
But Senator Joseph Biden of Delaware, the top Democrat on the Senate Foreign Relations Committee, said Goss' statement does not comport with what he heard on a recent visit to Iraq.
"I wish Porter Goss would speak to his intelligence people on the ground," Biden said on CBS's "Face the Nation". "They didn't suggest at all it was near its last throes. Matter of fact it's getting worse, not better," Biden said.
Attacks such as the restaurant
bombing reflect a security crisis
Bush said Iraq presented a "vital test" for American security. "The mission isn't easy, and it will not be accomplished overnight," he said on Saturday in his weekly radio address.
US Secretary of State Condoleezza Rice said any withdrawal of US troops will depend on Iraq's ability to handle its own security, and said events are moving in the right direction.
"The security forces of Iraq are getting better. We're making progress, making steady progress. They're not yet ready but they are taking over every day more and more of what the coalition has done. And that will mean that there is less need for coalition forces," she told "Fox News Sunday".