For all of the Republican handwringing over President Obama's use—or overuse—of executive authority, there is one exclusive presidential power he has barely wielded at all: the veto.

Obama has rejected just two bills passed by Congress in his nearly six years in office. That's the fewest of any president since James Garfield, who didn't veto a single bill, but lasted only six months in the White House before his assassination in 1881. And when you look at presidents who have served as long as Obama has, you'd have to go back to James Monroe, the nation's fifth president, to find a chief executive who has formally clashed with Congress so rarely. Monroe vetoed just one bill in his two terms, according to records kept by the Senate.

That's about to change for Obama in January, when Republicans control both the House and the Senate. For the last four years, the president has issued dozens of veto threats, but Majority Leader Harry Reid has kept conservative House bills from reaching his desk.

Yet Obama could face a veto decision even before the new Congress takes office, thanks to the fresh post-election push to approve the Keystone XL oil pipeline. The House passed legislation on Friday signing off on construction of the TransCanada project by a bipartisan vote of 252-161, as 31 Democrats joined all but one Republican in support. The Senate plans to vote on the bill next week following a demand by Mary Landrieu, the Louisiana Democrat who is fighting to retain her seat in a run-off election scheduled for December 6. Landrieu made a big push for the legislation during a floor speech on Wednesday, and with the support of moderate Democrats, she appears to be nearing the 60 votes needed to pass it. Even if it falls short next week, Republicans are sure to put it over the top in January.