WASHINGTON (AP) -- The White House issued its second veto threat since Republicans took full control of Congress, saying Wednesday that President Barack Obama would block legislation to increase his health care law's definition of a full-time worker from 30 to 40 hours per week.
The announcement came a day after Obama's spokesman said he would veto the first bill of the new Senate -- a measure to approve construction of the Keystone XL pipeline to carry Canadian oil into the U.S.
Lawmakers formally opened the new session of Congress on Tuesday with the Republicans in charge of both the Senate and the House of Representatives for the first time since Obama took office. The party's sweep of the November elections is certain to complicate the final two years of Obama's presidency as he seeks to cement his policies on health, the environment and immigration.
Republicans argue that the health law's 30-hour requirement is encouraging companies to cut workers' hours. The House plans to debate the measure this week as one of its first orders of business in the new Congress.
The White House said in statement there is no evidence the law has caused a broad shift to part-time work, and the nonpartisan Congressional Budget Office projected that the legislation would mean 1 million fewer people receiving health coverage at work.
The health care law, Obama' signature domestic achievement, has extended insurance coverage to millions of Americans who previous lacked it. Republicans have criticized the law, which was passed in 2010, for requiring Americans to carry insurance or face penalties. They also warn that it will worsen health care in the U.S.
The Senate minority leader, Sen. Harry Reid, warned in a statement Wednesday that Democrats wouldn't acquiesce to attempts to undo Obama's health care law or protections for workers.
"I have no intention of just rolling over," Reid said. "I can't. Not when the middle class is teetering on the verge of extinction."
The new majority leader, Sen. Mitch McConnell, spoke optimistically of working with Obama and Democrats on issues such as trade agreements, infrastructure improvements and rewriting tax laws.
But he took a jab at Obama for threatening to veto the pipeline bill.
"Threatening to veto a jobs and infrastructure bill within minutes of a new Congress taking the oath of office -- a bill with strong bipartisan support -- is anything but productive," McConnell said of the veto promise issued by the White House Tuesday as lawmakers were formally opening the 114th Congress.
Democrats responded by blaming Republicans for gridlocking the Senate when they were in the minority.
The Keystone XL pipeline project, which is highly important to Canada's government, would move tar sands oil from Canada 1,179 miles (1,900 kilometers) south to Texas refineries on the Gulf of Mexico. Supporters say it would create jobs and ease American dependence on Middle East oil. A government environmental impact statement also predicted that a pipeline would result in less damage to the climate than moving the same oil by rail.
Critics argue that the drilling itself is environmentally harmful and the pipeline would provide few permanent jobs, while any leaks could threaten the aquifer in the agricultural heartland. They said much of the Canadian crude would be exported with little or no impact on America's drive to reduce oil imports, which have already been greatly reduced because of record U.S. oil production.
Meanwhile, House Republicans began the new Congress with old divisions on display Wednesday, bitter fallout from a failed rebellion against Speaker John Boehner.
Boehner took swift action against two of the dissenters, knocking them from a key committee. But some of his allies demanded more, furious at the two dozen lawmakers who opposed him in Tuesday's speaker vote.
"All of us think that they should have retribution," said Rep. Devin Nunes, a Boehner loyalist. "They put the conservative agenda at risk with their wanting to be on television and radio."
Other lawmakers counseled caution, urging Boehner not to crack down on his opponents and instead focus on substantive issues.
The rebels themselves warned of their own payback if Boehner does take further steps against them.
"There's going to be a fight," said Rep. Louie Gohmert, a Boehner foe, when asked what would happen if leaders retaliated. "And it's going to be real hard to bring the party together like they say they want to do."