The United States should set a limit on the number of US troops in Iraq but increase numbers in Afghanistan, Senator Hillary Clinton has said.
Senator Clinton's remarks come as the US presidential race hots up
Mrs Clinton, a likely candidate for the Democratic presidential nomination, recently visited both countries.
She joins other senior US politicians in opposing the president's plans to send 21,500 extra troops to Iraq.
The Democrats, who control Congress, have promised to hold non-binding votes on George W Bush's strategy.
Democratic Senators Joe Biden and Carl Levin, together with Republican Chuck Hagel, have introduced a resolution opposing the plan.
"I will do everything I can to stop the president's policy as he outlined it Wednesday night," said Sen Hagel, a potential 2008 presidential candidate.
Correspondents say that Republicans will find themselves in a difficult position: they must either opt to stay loyal to Mr Bush and risk angering voters disillusioned by the war or go against the party line.
Meanwhile Madeleine Albright, US secretary of state under Democratic President Bill Clinton, described the Bush strategy as less a statement of policy than a prayer.
"It was not about reality. It was about hope. But hope is not a strategy. Iraqis will continue to act in their own best interests as they perceive them and we must act in ours," she told a hearing at the House of Representatives Foreign Affairs Committee.
Senator Clinton, who was on her third trip to Iraq, said she was against increasing US troops there.
"I am opposed to this escalation," Mrs Clinton told CBS News.
"I am for putting more troops in Afghanistan," she said, describing Afghanistan as one of the "great missed opportunities".
US forces should be boosted there before an expected spring offensive by the Taleban, she said.
Senator Clinton said she wanted the US government to impose conditions on funding for Iraq's military and economic reconstruction to force Iraq into achieving certain political goals.
She also criticised the failure of Prime Minister Nouri Maliki's government to stem the growing civil conflict between Sunnis and Shias.
Mrs Clinton's comments come a day after the race for the Democratic nomination in the 2008 presidential election hotted up with Senator Barack Obama announcing he had formed an exploratory committee which would allow him to raise money and hire staff for a campaign.
Mr Obama, who was elected to the Senate in 2004, has consistently opposed the war in Iraq.
Mr Bush has urged his opponents to come up with ideas
Another Democratic presidential hopeful, Senator Christopher Dodd, is pushing for legislation that would require President Bush to get congressional approval before he could send additional troops to Iraq.
He argues that the mission in Iraq has changed dramatically since Congress gave Mr Bush broad authority to conduct the Iraq war in October 2002, a measure Mr Dodd himself supported.
In the House of Representatives, three Democrats, Lynn Woolsey, Barbara Lee and Maxine Waters, have introduced a bill calling for the full withdrawal of US forces from Iraq within six months.
They see it as a comprehensive alternative to the Bush administration's new Iraq strategy.
For his part, Mr Bush has been trying to garner support for his Iraq plans strategy, which includes the "surge" force of 21,500 troops.
He has repeatedly said that withdrawing troops from Iraq would amount to failure.