WASHINGTON — Senior Republican officials have met at the White House to synchronize strategies. House Democrats issue daily countdowns as the moment approaches. Both sides are planning major operations next week to try to gain the high ground.

With near military precision, Democrats and Republicans are laying the groundwork for the coming congressional testimony of Gen. David H. Petraeus, the top American commander in Iraq, and Ryan C. Crocker, the American ambassador there.

Lawmakers see joint appearances by the two men before four separate congressional committees on Tuesday and Wednesday as a crucial opportunity to shape public opinion on the future of the war before the November elections.

"The current Iraq strategy has no discernible end in sight," Democratic congressional leaders wrote on Friday to President Bush, urging him to again consider a significant change in Iraq policy.

For Democrats, the preparation is driven in part by the memory that they were knocked badly off message during Petraeus' last appearance in September, when the liberal advocacy group MoveOn.org took out a full-page newspaper advertisement that labeled the general "Betray Us" and provided a rallying cry for Republicans. Officials at MoveOn.org declined on Friday to discuss any advocacy plans they might have for this round of hearings.

Democrats intend to emphasize the direct and indirect costs of the 5-year-old war and what they see as a drain on the military, a lack of political progress in Iraq, and the Bush administration's uncertain endgame for American involvement. They would clearly like to keep the focus on proceedings inside the hearing rooms, rather than get caught up in a dispute over outside advocacy groups.

"I'm a big proponent of the First Amendment," said House Speaker Nancy Pelosi. "But I would hope that as we set the stage for Gen. Petraeus' appearance before the committee, it is by shining a bright light of truth and a mirror on what he has to say and see how that is consistent with our greater national security goals."

On the Republican side, a veterans' group tied to the party is planning a rally near the Senate, while House Republicans are coordinating with conservative bloggers and will invite conservative radio commentators to broadcast from Washington. Republicans plan to push for new money for troops in Iraq; to highlight statements by Democrats that the troop "surge," which ended last fall, has worked; to point out some signs of political reconciliation; and to insist that troops can be removed from Iraq only when military leaders decide it is the proper time.

"The goal of the effort is not just to reinforce the message delivered by Gen. Petraeus, but to launch a full-fledged assault on the misinformation campaign promoted by Democratic leaders who have lost every time they have tried to legislate defeat for America," said an internal strategy memo for Republican communications operatives.

The hearings are also likely to be a major platform for the presidential candidates, with all three senators running for the White House — John McCain of Arizona, Hillary Rodham Clinton of New York and Barack Obama of Illinois — sitting on the relevant committees. McCain, a strong supporter of the war, is the ranking Republican on the Armed Services Committee, a position that entitles him to be the first Republican to speak and question the officials. Clinton is a more junior Democratic member of the panel.

"I love the idea of McCain having to explain what is going on here and why this is working so well," said Sen. Joseph R. Biden Jr., Democrat of Delaware and chairman of the Foreign Relations Committee.

But Biden, whose committee includes Obama, a fellow Democrat, and will hear from Petraeus and Crocker as witnesses, said he would not have Obama leapfrog more senior members of the panel to give him a more prominent role; that would smack too much of politics, Biden said. Sen. Carl Levin, D-Mich., the chairman of the Armed Services panel, said the same of Clinton.

"There will be no change in our usual approach," said Levin, who in a conference call with reporters said Americans do not want such life-and-death matters as oversight of the war turned into purely partisan displays.

Yet leaders of both parties anticipate hearing little new and expect Petraeus to recommend at least a temporary halt in troop withdrawals. With Democrats unable to muster the votes to force a change, lawmakers say it appears Bush's tenure will come to a close next January with well over 100,000 troops remaining in Iraq.

"You can only stretch a military so far," said Rep. Ike Skelton, D-Mo., the chairman of the House Armed Services Committee. "And I'm fearful that the Iraqi conflict is draining them far beyond where they should be."

The run-up to the testimony showed how the factions were searching for advantage. Republicans jumped on a comment by Pelosi warning Petraeus to "not put a shine" on the recent conflict in Basra, portraying it as a success when questions still surround the Iraqi operation. Republicans quickly accused her of questioning the general's credibility, but the charge gained little traction.

Before Petraeus' appearance last fall, Republicans feared a rush of defections to join Democrats in calling for troop withdrawals. But the general's appearance — and a backlash to the MoveOn advertisement — helped stabilize Republicans. Democrats have been unable to win support from more than a handful of Republicans for proposals to set a deadline for troop withdrawal, leaving the parties at a stalemate.

Republicans will use the hearings to argue that Democrats are ignoring the gains made under the surge in an effort to placate anti-war advocates.

"Gen. Petraeus comes back in a different situation, in many ways a vastly improved situation, from the situation he was in a year ago or six months ago," said Rep. Roy Blunt of Missouri, the No. 2 House Republican. "I think our friends on the other side will have a hard time rewriting the facts of that."

But Democrats say the hearings should look beyond military gains from the surge.

"We saw a meaningful reduction in violence, and that presented an opportunity to build up national reconciliation that was the underlying premise of the surge," said Rep. Howard L. Berman, D-Calif., the chairman of the House Foreign Affairs Committee. "It seems that the Iraqis have largely frittered it away."