WASHINGTON — Congressional Democrats stepped hungrily to the brink of power yesterday, promising immediate action to limit the influence of lobbyists and constant prodding of the Bush administration to bring American troops home from Iraq.

President Bush pushed back against the political opposition as he contemplated divided government for the first time since entering the White House. He said he would soon propose a five-year plan to balance the budget, and he challenged Democrats to avoid passing “bills that are simply political” statements.

“There is nothing political about finding a policy to end the war in Iraq, raising the minimum wage, achieving energy independence or helping kids afford college,” shot back Senator Reid of Nevada, who is due to become majority leader at the stroke of noon today. “In fact, politics has prevented progress on these issues for too many years.”

Even as they prepared to take control of Congress, Democrats received a brusque reminder that they face pressure from the political left as well as resistance from Republicans.

At one point during the day, Rep. Rahm Emanuel, a member of the Democratic leadership, was addressing reporters when he was loudly interrupted by Cindy Sheehan and other anti-war activists. “De-escalate, investigate, troops home now!” they shouted, while he smiled gamely.

Rep. Nancy Pelosi, in line to become the nation’s first female House speaker, spent much of her day at ceremonial events. She attended a Catholic Mass in remembrance of the children of Darfur and Katrina, then a tea in her honor.

That left it to her lieutenants to outline plans for the Democrats’ initial stretch in the majority.

Rep. Steny Hoyer of Maryland, the incoming majority leader, said the first six bills and a series of stiffer ethics rules would be passed within two weeks.

The first step, he said, would take place by early evening today, and consist of several measures crafted in response to the scandals that weakened Republicans in last fall’s elections.

In addition to expanding restrictions on privately financed trips enjoyed by lawmakers, House Democrats said they will prohibit travel on corporate jets and require greater disclosure of earmarks, the pet projects inserted into legislation at the behest of individual lawmakers.

The rules do not prohibit lawmakers from taking trips financed by foundations that seek to influence public opinion. Those trips will require pre-approval from the ethics committee.

Current rules ban congressional travel paid for by lobbyists or foreign governments, and violations of the existing restrictions played heavily in the scandal involving Republican lobbyist Jack Abramoff.

Democrats appeared to backtrack from their campaign-season pledge in at least one area. They were sharply critical last year of Republicans for keeping a roll call vote open for hours so leaders could find enough votes to pass Medicare legislation. But rather than ban the practice, the proposed new rule declares that a vote “shall not be held open for the sole purpose of reversing the outcome.”

Two months after the voters ordered a change in congressional control, Democrats and Republicans in the House and Senate, as well as Mr. Bush, pledged to work in a bipartisan spirit.

“Democrats are committed to working with Republicans to get results,” Mr. Reid wrote in a memo distributed to the party’s rank-and-file. He said an unprecedented all-senators meeting set for today morning would “allow us to start off on the right foot, as colleagues instead of adversaries.”

Those promises could scarcely obscure the political jockeying under way.

After long pledging a new era of civility and openness in the House, Democrats said they would not allow Republicans the chance to amend any of the first half-dozen bills to be brought to a vote during the first 100 hours of the new Congress.