Senate Majority Leader Mitch McConnell blasted President Obama on Wednesday for vowing to veto the first bill of the new, Republican-controlled Senate -- legislation to approve the controversial Keystone XL oil pipeline. 

In his first major floor speech as majority leader, the Kentucky Republican pushed for bipartisan cooperation on major issues but said it could "only be achieved if, if, President Obama is interested in it." 

He added: "And I assure you, 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's top lieutenants echoed his concerns, with Senate Majority Whip John Cornyn, R-Texas, calling the "premature" veto threats "deeply irresponsible and troubling." 

The White House on Tuesday threatened to veto two pieces of legislation being produced by the new Congress -- one related to ObamaCare and the economy, and the other on the Keystone pipeline. On Wednesday, the White House issued formal statements vowing to veto the bills. 

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On the Keystone bill, the White House claimed the legislation would prevent "the thorough consideration of complex issues that could bear on U.S. national interests." 

The Obama administration wants to let a separate State Department review process play out, though pipeline supporters complain that process already has been underway for years. 

The veto threat over Keystone sets up a looming showdown between Obama and the GOP-controlled Congress, while underscoring the deep tensions likely to persist as majority Republicans challenge the president's agenda during his final two years in office. 

As the Senate moves ahead with its own legislation -- with sponsors claiming to have more than enough votes to pass it -- the House is set to vote on its version on Friday. 

One of the sponsors, Sen. John Hoeven, R-N.D., told Fox News he expected a veto threat but predicted: "We're going to win on the merits." 

If the legislation passes and Obama vetoes, supporters in Congress would need to muster a two-thirds majority to override -- or try and attach the measure to a separate piece of legislation. 

The $8 billion oil pipeline would run from Canada's oil sands to the Texas Gulf Coast. It has become a symbol of divisions over the country's energy and environmental policy. 

Republicans argue that the project would create jobs and reduce U.S. dependency on oil from the Middle East. 

Obama downplayed the potential benefits of pipeline in late December and claimed it would not lower gas prices for Americans -- but instead would help Canadian oil companies. 

The 1,179-mile project is proposed to go from Canada through Montana and South Dakota to Nebraska, where it would connect with existing pipelines to carry more than 800,000 barrels of crude oil a day to refineries along the Texas Gulf Coast. 

Despite the disagreement over Keystone, McConnell seemed optimistic that both parties in the Senate could work together on other measures such as strengthening Medicare and Social Security, revamping tax laws and working "to balance the budget and put our growing national debt on a path to elimination." 

Meanwhile, the White House threatened to veto legislation that would increase his health care law's definition of a full-time worker from 30 to 40 hours per week. 

Republicans say the health law's 30-hour requirement is encouraging companies to cut workers' hours. The White House said in statement Wednesday there is no evidence the law has caused a broad shift to part-time work. The House plans to debate the measure this week as one of its first orders of business in the new Congress. 

The White House argues the bill would reduce the number of Americans with employer-based health insurance coverage and create incentives for employers to shift employees to part-time work. 

House Speaker John Boehner, like McConnell, lamented the early veto threats. 

"Unfortunately, by threatening two of these bipartisan jobs bills, the president essentially is telling the American people he really doesn't care what they think," he said. 

Amid the dispute over veto threats, Obama visited a Ford assembly plant in Michigan on Wednesday to tout the auto industry's recovery -- as part of the run-up to his State of the Union address. 

Obama declared the worst of the financial crisis "is behind us" and touted that auto companies have repaid taxpayers for the crisis-era bailout. 

"The auto industry has proved that any comeback is possible," Obama said. 

The Associated Press contributed to this report.