Washington ? President Bush and the Democratic-controlled Congress lurched toward a veto showdown over Iraq on Wednesday, the commander in chief demanding a replenishment of war funding with no strings and Speaker Rep. Nancy Pelosi counseling him, “Calm down with the threats.”

Bush said imposition of a “specific and random date of withdrawal would be disastrous” for U.S. troops in Iraq and he predicted that lawmakers would take the blame if the money ran short.

“The clock is ticking for our troops in the field,” he said. “If Congress fails to pass a bill to fund our troops on the front lines, the American people will know who to hold responsible.”

Bush spoke as the Senate moved toward passage of legislation that would require the beginning of a troop withdrawal within 120 days, and would set a goal of March 31, 2008, for its completion.

The House approved a more sweeping measure last week, including a mandatory withdrawal deadline for nearly all combat troops of Sept. 1, 2008.

Both bills would provide more than $90 billion to sustain military efforts in Iraq and Afghanistan.

After passage, the next step would be a House-Senate compromise measure almost certain to include conditions that Bush has said he finds objectionable, and the president’s remarks seemed designed to lay the political groundwork for a veto showdown with the new Democratic majority.

Confidently predicting his veto would be sustained in Congress, he said, “Funding for our forces in Iraq will begin to run out in mid-April. Members of Congress need to stop making political statements and start providing vital funds for our troops. They need to get that bill to my desk so I can sign it into law.”

House Speaker Pelosi, D-Calif., responded to Bush with a blend of conciliation and challenge.

“On this very important matter, I would extend a hand of friendship to the president, just to say to him, ‘Calm down with the threats,'” she said. “There’s a new Congress in town. We accept your constitutional role. We want you to accept ours.”