Approval of the Keystone XL pipeline has become a point of friction in American politics, pitting environmental activists and liberals (who oppose it) against business interests, Republicans and moderate/embattled Democrats (who support it). With control of the Senate hinging on November, it's worth remembering how much Senate control could influence what happens to the pipeline.

And that is: Almost none. On Wednesday, Nov. 5, 2014 -- even on Jan. 31, 2015, the fate of the Keystone XL pipeline will still be in Obama's hands.

First of all, it's important to understand why the project hasn't moved forward. The pipeline proposed by TransCanada would shunt a form of oil from fields in Hardisty, Alberta, Canada, to Steele City, Neb. Since it would cross the boundary between the United States and Canada, TransCanada has been awaiting a permit from the State Department. For years, mind you; the original application was submitted in 2008 and considered by the agency in 2010, when Hillary Clinton was Secretary of State. With the 2012 election looming and under pressure from a deadline set by congressional Republicans, President Obama rejected the permit. But TransCanada reworked its application, which has moved through a second environmental review and been waiting for a final decision for months.

The key actor is Obama. It is within his power, as overseer of State, to grant or deny the application. During a speech in 2013, he unexpectedly set a new requirement for approval: that the pipeline "not significantly exacerbate the climate problem." Were he to make the decision tomorrow, it's not clear how he would decide, especially given new research suggesting that approval of the pipeline would increase global oil consumption by 0.6 barrels for every barrel of oil produced by the pipeline, given the decrease in oil prices.

Congress has repeatedly tried to wrench the decision away from him. Sen. Mary Landrieu (D-La.) introduced a bill with Sen. John Hoeven (R-N.D.) earlier this year that would grant the permit without the State Department needing to weigh in. It's become a key part of her difficult battle for reelection, and it was announced at the website of the Senate Energy and Natural Resources Committee, which she chairs, alongside a long list of her efforts to get approval. The conservative Washington Times offered one way in which her efforts aren't an unalloyed political victory, suggesting that the bill won't go anywhere unless Landrieu convinces Senate Majority Leader Harry Reid (D-Nev.) to bring it to a vote.

That's where the argument that a Republican Senate would approve Keystone comes into play. News outlets like the Christian Science Monitor and Vox suggest that rubber-stamping Landrieu's bill would be a top priority of a Republican-led Senate, should November go their way. (Maybe not specifically Landrieu's bill. If the Republicans retake the Senate, there is a good chance it's because Landrieu lost her race.) Sen. Jim Inhofe (R-Okla.) made the case for action from a Republican Senate explicitly earlier this year.

The problem for a newly empowered Republican Senate, though, is that passage of the bill would still need to be signed into law -- by the president. Meaning that Congress would be swapping one decision from Obama (on the permit) with another (approving a bill that eliminates the need for the permit).

Khary Cauthen, senior director of federal relations at the American Petroleum Institute, thinks that the president would approve that bill. "I think at that point," he told the Post by phone, "the president would have to realize that the legislators are doing what they've heard from their constituents." Cauthen repeatedly pointed out that legislative backing of approval is bipartisan (as the leadership of Landrieu suggests) and to polling which shows broad public support for the pipeline. While the 2014 elections wouldn't necessarily change the either/or dynamic of approval, Cauthen did note that "if [passage] happens post-election, this would be representative of what the voters have said. And the voters want the pipeline." If voters choose a Republican-led Senate, in other words, there's more pressure on Obama to sign off.

It's fair to be more skeptical. The president has reserved the final decision for himself for years, and articulated the (vague) standard he thinks must apply. So what if he vetoes a proposal passed by Congress? Then it goes back to Congress, which can attempt to override it. That would require two-thirds votes in the House and Senate, meaning that at least a dozen Senate Democrats (depending on the 2014 elections) and probably at least 50 Democrats in the House would have to be willing to buck Obama's will. That's a very tall order.

Which clearly doesn't mean that Keystone won't continue to be played for politics. In Michigan, the injection into the Senate race of independent support from environmentalist Tom Steyer has resulted in blowback. Republican Terri Lynn Land has run ads criticizing Steyer for opposing Keystone and suggesting that Democratic Rep. Gary Peters should be faulted as well. Steer, meanwhile, has hammered Landrieu for her support of the proposal.

But the power to approve or reject the pipeline remains where it always has: with the one elected official in Washington, D.C. who doesn't have to worry about reelection.