WASHINGTON — President Barack Obama pushed urgently Thursday for passage of legislation to confront global warming, billing it as a job-creating machine rather than the costly "job killer" Republicans denounced and telephoning wavering Democrats on the eve of what could be a historic House vote.

Speaking in the Rose Garden at the White House, Obama said Washington must not miss the opportunity to work on cleaning the air, creating new "green" energy jobs and moving the nation away from its reliance on fossil fuels such as oil, coal and natural gas.

The White House appeared concerned that momentum for the bill was slipping, though White House press secretary Robert Gibbs said that when it came time for a House showdown, "I'd bet on the president."

Democratic leaders scurried to line up enough votes to get the bill passed. They enlisted former Vice President Al Gore, the country's most prominent voice on the urgency of addressing climate change, to make phone calls to wary lawmakers — including some who believe the House bill was too weak rather than too strong.

House Republicans for weeks have maintained a drumbeat against the legislation, calling it a massive energy tax on every American and a "job killer" because it will force higher prices on electricity, gasoline and other energy sources as the economy shifts from cheaper fossil fuels, or as companies and utilities are forced to buy pollution allowances.

Obama as well as House Speaker Nancy Pelosi, D-Calif., sought to counter that argument.

"This is going to be a close vote because of misinformation out three that there's somehow a contradiction between clean energy and economic growth," said Obama. Rather than emphasizing any impact on pollution or global warming, he called the House legislation "a jobs bill" that will lead to the creation of new industries and "finally make clean energy a profitable kind of energy."

"It will create millions of new jobs," echoed Pelosi at a Capitol Hill press conference.

The Senate, meanwhile, was waiting for the House to act. Approval of a climate bill in the Senate has been viewed as a long shot because it would require 60 votes to overcome a certain filibuster. And that has made a decision by some House Democrats to vote for the politically charged bill even harder since final passage is so much in doubt.