WASHINGTON — In command and ready for a fight, defiant Republicans ignored two White House veto threats and advanced bills in Congress Thursday curbing President Obama’s cherished health care overhaul and forcing construction on a proposed oil pipeline. The top House Democrat predicted her party would uphold both vetoes.

On the new Congress’ third day of work, a Senate committee approved a measure dismantling Obama’s ability to block the Keystone XL oil pipeline, which has become a flashpoint pitting the GOP’s jobs agenda against Democrats’ environmental concerns. The Senate planned to begin debate next week and passage there seemed likely, while the House was poised to approve its version Friday.

Meanwhile, the House approved legislation narrowing the definition of full-time workers who must be offered employer-provided health care from those working 30 hours weekly to a 40-hour minimum. The vote was a mostly party-line 252-172 – short of the 290 needed, assuming all members voted, for the two-thirds majority required to override a veto.

On both bills, GOP leaders would face uphill fights mustering the two-thirds House and Senate majorities needed to override vetoes. But both measures had some support from Democrats, and Republicans could use them to portray themselves as championing bipartisan legislation, only to be thwarted by Obama and his Democratic allies.

“Given the chance to start with a burst of bipartisan productivity, the president turned his back on the American people’s priorities,” House Speaker John Boehner, R-Ohio, told reporters Thursday, adding, “We were taking our oath of office when they were issuing veto threats. Come on.”

House Minority Leader Nancy Pelosi, D-Calif., said Democrats would sustain Obama’s vetoes on both bills and said it was Republicans who have blocked progress.

She said Democrats would uphold a promised Obama veto on a third measure rolling back some regulations on the financial industry enacted after the 2008 economic crash. That bill fell short in the House this week but is expected to pass on a re-vote next week.

Obama’s 2010 health care law, a perennial GOP target, is phasing in a requirement that companies with more than 50 full-time workers offer health care coverage or face penalty payments to the government.

Backed by the U.S. Chamber of Commerce and other business groups, Republicans say defining full-time employees as those working at least 30 hours is pressuring firms to save money by cutting workers’ hours and diminishing the number of full-time jobs.

House Republicans say boosting the standard to 40 hours would protect those workers and named their bill the “Save American Workers Act.” They cite a study by the conservative Hoover Institution saying that 2.6 million workers are at risk of having their hours reduced by the 30-hour minimum, including disproportionately high numbers of female, low-income, younger and less-educated workers.

“You say you care about low-income workers, about working women and small businesses?” House Majority Leader Kevin McCarthy, R-Calif., taunted Obama. “Show it and sign this bill.”

The White House and Democrats, with support from labor and liberal groups, mock the measure as the latest attempt by Republicans to scuttle Obama’s health care law. The House has voted more than 50 times to repeal or roll back parts of that law since Republicans took control of the chamber in 2011.

Democrats say changing the full-time threshold from 30 to 40 hours would make fewer workers eligible for employer-provided health coverage and put more of them at risk of losing that coverage from companies looking to cut costs. That’s because of sheer numbers: While just under 10 percent of employees were working 30 to 34 hours weekly, 41 percent were working 40 hours alone, according to November 2014 figures from the federal Bureau of Labor Statistics.