US Secretary of Defense Robert Gates said in Baghdad on Monday that he was in favor of a short pause in troop drawdowns from Iraq after about 30,000 soldiers have been sent home by July.
In the southern port city of Basra, meanwhile, two journalists working for the US channel CBS News were kidnapped by gunmen, staff at their hotel said.
Gates said the security situation in Baghdad remained "fragile," a comment echoed on the streets of the capital which was rocked by two car bombings that left 19 people dead just as he was winding up his surprise trip to Iraq.
"I think that the notion of a brief period of consolidation and evaluation probably does make sense," he told reporters after a two-hour meeting with the US commander in Iraq, General David Petraeus.
"I must say, in my own thinking, I am headed in that direction as well but one of the keys is how long is that period and what happens after that. It still has to be determined and decided by the president," he said.
The 157,000-strong US force in the insurgency-wracked country is currently on track to come down from 19 brigades to 15 by July, a reduction of at least 20,000 troops plus another 7,000 to 10,000 members of support units, according to military commanders in Iraq.
Gates has previously expressed the hope that the drawdown can continue to about 10 brigades or about 100,000 troops by year's end.
Petraeus is supposed to make recommendations in April on US force levels for the second half of the year. Last month he suggested in an interview with CNN that he will ask for a pause in the drawdown to assess whether security can be maintained with fewer troops.
It is not clear how long a pause Petraeus has in mind, but reports have varied from 30 to 90 days.
Gates arrived in Iraq on Sunday on his seventh visit shortly before the first anniversary of a US troop surge designed to improve security in Baghdad, although the country continues to battle a deadly insurgency.
Back in Washington, Democratic White House hopefuls Barack Obama and Hillary Clinton rejected the idea of pausing the troop drawdowns.
"I strongly disagree with the administration's plans to `pause' the long overdue removal of our combat brigades from Iraq," Obama said in a statement.
"We cannot wage war without end in Iraq while ignoring mounting costs to our troops and their families, our security and our economy."
Clinton said she was "disheartened" by the remarks made by Gates, after he met the US commander in the country General David Petraeus.
"This means that we will have as many troops in Iraq in the summer of 2008 as we had at the beginning of 2007," Clinton said.
"I continue to call on the President to end the war he started, to take responsibly for bringing our young men and women home."
In Basra, a staff member at the Palace Sultan Hotel told reporters that two journalists working for CBS News were led away at gunpoint by a gang of about 10 gunmen on Sunday.
"Yesterday a group of about 10 men in civilian clothes arrived at the hotel during the day and made inquiries about who was staying there," the staff member said.
"They returned later in a SUV. They were armed," the staff member said, adding that the two journalists were taken away at gunpoint.
"All efforts are under way to find them and until we learn more details CBS News requests that others do not speculate on the identities of those involved," the network said.