Washington (CNN) -- President Obama worked behind closed doors to win support among key House Democrats for his health care reform plan Thursday, one day after urging Congress to hold a final up or down vote on the measure.
The administration also ratcheted up its campaign against private health insurance companies, summoning a group of CEOs to the White House and asking them to justify recent rate increases.
Senior Democrats, meanwhile, continued to give optimistic predictions about the fate of the president's top domestic priority. House Speaker Nancy Pelosi said Congress is "on the brink of making very important history."
White House Press Secretary Robert Gibbs said he thinks the House of Representatives is on schedule to pass the Senate health care bill before Obama leaves for an overseas trip March 18.
Asked to describe Obama's strategy for convincing wavering Democrats, Gibbs said the president is simply describing "the benefits of the legislation" and "why it's important for our country."
"I have confidence that [Congress will understand] what's good for them and good for America," Gibbs added.
On Wednesday, Obama urged Congress to bring the yearlong debate on health care reform to a close. He argued that his nearly $1 trillion proposal is a compromise plan that combines the best ideas of Democrats and Republicans.
He also came out in support of a legislative bypass known as reconciliation, which would allow changes to the health care bill to be passed by the Senate with only 51 votes, a simple majority.
"At stake right now is not just our ability to solve this problem but our ability to solve any problem," he said. "The American people want to know if it's still possible for Washington to look out for their interests and their future. They are waiting for us to act."
Top Republicans have said repeatedly that Obama's proposal amounts to a government takeover of the private health care system that will do little to control spiraling medical inflation.
In recent weeks, they have repeated their calls for the president to scrap his plan and start over. GOP leaders also fiercely oppose the use of reconciliation, arguing that it was never meant to be used for such a major policy change.
Multiple Democratic sources have said the emerging consensus plan is for the House of Representatives to pass the Senate bill and send it to Obama. A package of changes that mirror the president's plan would then be passed through both chambers under reconciliation rules.
Pelosi said Thursday that she feels very confident that the changes passed under reconciliation "will satisfy [House] members' concerns about the Senate bill."
Democrats increasingly raised the possibility of using reconciliation after losing their 60-vote filibuster-proof Senate majority in January, when GOP Sen. Scott Brown won the Massachusetts Senate seat held by the late Sen. Ted Kennedy, a Democrat.
Observers note, however, that it remains unclear exactly which health care provisions can be approved under reconciliation, which is reserved for legislation pertaining to the budget. Senate Republicans can also propose an unlimited number of amendments to bills brought up under the procedure.
Another potential problem for Democratic leaders is abortion. House Democrats in favor of abortion restrictions have warned repeatedly that they cannot vote for the Senate health care bill.
The bill that passed the House would prohibit abortion coverage in policies made available through health insurance exchanges to people receiving federal subsidies. The less restrictive Senate bill would allow individuals purchasing plans through the exchanges to pay for abortion coverage out of their own funds.
Most observers do not believe that abortion provisions in the health care bills can be changed under the rules of reconciliation.
Pelosi tried Thursday to assuage the concerns of abortion-rights opponents.
"If you believe that there should be no federal funding of abortion, and if you believe there should be no change in the [current federal] policy, and if you believe that we need health care all for Americans, we will pass the bill," she said.
"And we will pass the bill."