The withdrawal of US troops is a key issue in the presidential campaign
Democratic opponents of US President George W Bush have accused him of putting off tough decisions on Iraq until after the presidential elections.
The criticism follows Mr Bush's announcement of a "major strategic shift" that includes suspending troop withdrawals after July.
He says this would allow senior commander General David Petraeus to assess the next step in Iraq.
But his opponents say the people want answers from this president, now.
The decision to halt withdrawals means the US presence in Iraq is likely to last well beyond January 2009, when Mr Bush will leave office and whoever wins the November elections will take over.
The Democratic Speaker of the House Nancy Pelosi said the president had failed to answer key questions, including what conditions would allow troops to come home.
"The president has taken us into a failed war, he's taken us deeply into debt and that debt is taking us into recession," she said. "We need some answers from the president."
By July, the US presence in Iraq should be reduced from 20 brigades to 15 - leaving about 140,000 troops in the country, about the same number as were present before the troop surge began in early 2007.
The president said there had been significant military, political and economic progress in Iraq since then, and that "today we have the initiative".
Democratic leaders did welcome Mr Bush's shortening of combat tours from 15 to 12 months, but said keeping troops committed to Iraq was unacceptable.
The speech "can only be described as one step forward and two steps back," said the leader of the Democrats in the Senate, Harry Reid.
US Defence Secretary, Robert Gates said he hoped Gen Petraeus would be able to make an assessment of further troop reductions later this year.
"A brief pause for consolidation and evaluation following a return to pre-surge troop levels will allow us to analyse the process and its effects in a comprehensive way," he told the Senate panel in Washington.
"I do not anticipate this period of review to be an extended one, and I would emphasise that the hope, depending on conditions on the ground, is to reduce our presence further this fall."
The BBC's Kim Ghattas, in Washington, says that dissenting voices are now being heard among Republicans as well, because of the high cost of the war, and the long-term agreements which are being negotiated between Iraq and the United States.
Iraq is one of the key battlegrounds of the election campaign, with Republican John McCain arguing for continued engagement while Democratic rivals Hillary Clinton and Barack Obama call for full withdrawal.