Washington ? The first of up to 20,000 additional U.S. troops will move into Iraq by month’s end under President Bush’s new war plan, a senior defense official said Tuesday. House Speaker Nancy Pelosi pledged to hold a vote on the increase, which many Democrats oppose.

Details of a gradual military buildup emerged a day before Bush’s planned speech to the nation, in which he also will propose a bit over $1 billion to shore up the country’s battered economy and create jobs, said a second U.S. official.

Bush is expected to urge friendly Mideast countries to increase their aid to Iraq but will ignore the recommendation of the bipartisan Iraq Study group that he include Syria and Iran in an effort to stanch Iraqi bloodshed nearly four years after the U.S. invasion, said the official, who spoke on condition of anonymity because the plan has not yet been announced.

Bush is expected to link the troop increase to promised steps by the Iraqi government to build up its own military, ease the country’s murderous sectarian tensions, increase reconstruction and enact a plan to distribute oil revenues among the country’s religious sects.

Even before he delivers his speech, Bush’s plan has drawn sharp criticism from the leaders of the new Democratic-controlled Congress. Senate Majority Leader Harry Reid said he hoped for a bipartisan measure that would declare, “We don’t support this escalation of the war.” If it passes, “the president’s going to have to take note of that. I think that’s the beginning of the end, as far as I’m concerned,” he said.

The president met during the day with lawmakers, practiced his speech and briefed key foreign allies, including calls to the leaders of Britain, Australia and Denmark. Bush was expected to practice his speech a couple of more times before addressing the nation at 9 p.m. EST today from the White House Library.

Under Bush’s plan, thousands of troops will be alerted that they may be needed in Iraq – including units already there whose service would be extended, or others that could be sent earlier than initially scheduled, said one official.

Moving first into Iraq would be the 2nd Brigade, 82nd Airborne Division, which is now in Kuwait and poised to head quickly into the country, the defense official said. The brigade, numbering about 3,500 troops, is based at Fort Bragg, N.C.

Other units, including Marine brigades in western Iraq, could be asked to extend their deployment. And the military buildup is also likely to include moving the aircraft carrier USS John C. Stennis into the Persian Gulf region, as a show of force and a warning to Iran and Syria.

There are already about 132,000 U.S. troops in Iraq.

According to the defense official, Bush also will discuss the need to address how often the Pentagon can tap the National Guard and Reserves, although he may provide few details. And Bush will again endorse the need to increase the size of the Army and Marine Corps.