As the U.S. Senate convened Tuesday for the first time since November’s election, its new Republican majority lost no time in making another bid to approve construction of the disputed Keystone XL pipeline project. Sen. John Hoeven, R-N.D. proposed legislation that would authorize the project which has become the focus of a major political showdown, while President Barack Obama reiterated his intention to veto such a bill should it reach his desk.

The proposed Keystone XL pipeline extension, which could bring as much as 830,000 barrels of crude tar sands oil from Canada to the United States daily, has been a political flashpoint for years. Environmental activists across the U.S. and Canada have made the project a symbol of U.S. energy policy and lobbied the Obama administration to deny authorization for its construction.

Many environmental activists believe averting the construction of Keystone XL might not have a major effect on carbon emissions and climate change — but they feel it would demonstrate the environmental movement’s ability to force the U.S. government into bucking the energy lobby in at least one major case.

Obama has responded by delaying a final ruling on the pipeline multiple times, and its fate remains up in the air. Because Keystone XL would cross the border with Canada, its construction requires the approval of the U.S. State Department and the White House. But Congressional Republicans, along with some conservative Democrats, have repeatedly offered up legislation that would take the final decision out of the executive branch’s hands and authorize construction.

The most recent attempt to approve the pipeline came in mid-November, after the 2014 election that catapulted the Senate Republicans to victory, but before the Senate Democrats formally relinquished power. The Republican majority in the House signed off on the pipeline on Nov. 17, but the proposal failed to achieve a filibuster-proof supermajority in the Senate the following day.

Now that the Senate Republicans hold the balance of power in the new session, they are preparing to try again. Don Stewart, press secretary for Senate Majority Leader Mitch McConnell, R-Ky., told Al Jazeera by email that the new Senate majority was prioritizing Keystone approval because it is “a bipartisan infrastructure bill that will create jobs.” The Senate is expected to begin debate on the legislation early next week.

Russ Girling, president and CEO of TransCanada, the energy company behind the pipeline, said on Tuesday that the firm is "greatly encouraged" by the introduction of the new legislation.

"We look forward to the debate and ultimately a decision by the U.S. Administration to build Keystone XL," he said.

This time the odds may be in favor of Hoeven’s bill, which was co-sponsored by Sen. Joe Manchin, a Democrat from West Virginia. Yet even if the legislation clears both the Senate and the House, it may still not be made law; the White House has said the president intends to veto the legislation if it reaches his desk.

“Republicans couldn’t have picked a worse time to push Keystone XL,” wrote Jamie Henn, spokesman for the anti-Keystone environmental group 350.org. “No one is feeling desperate for more oil right now. Meanwhile, the President’s opposition to the project and concern about climate change has never sounded stronger."

House Speaker John Boehner, R-Ohio, said in a statement that the president's veto threat was tantamount to saying "no to more American infrastructure, no to more American energy and no to more American jobs."

"Fringe extremists in the president's party are the only ones who oppose Keystone, but the president has chosen to side with them against the American people," said Boehner. "This is simply more evidence that President Obama is hopelessly out of touch and has no plans to listen to the American people or champion their priorities."

In order to defeat a presidential veto, both the House and Senate would need to return two-thirds majorities in favor of overriding the president’s wishes. Top Democrat Sen. Chuck Schumer, D-N.Y., said Sunday that his party had the votes to keep any veto of Keystone legislation from being overridden.

McConnell has offered Senate Democrats leeway to offer their own amendments to the Keystone XL legislation, and the minority party is likely to attach several additional proposals to the bill. Already, some Senate Democrats have proposed measures that would ban the export of oil transported through the pipeline and require that it be constructed with U.S.-made steel.

Leading Senate environmentalist Sen. Sheldon Whitehouse, D-R.I., is reportedly considering attaching some amendments of his own. A spokesman from the senator’s office said he was unable to provide details of what those amendments might look like.

Whatever the circumstances, Keystone XL approval legislation is likely to hit the Senate floor early next week. Debate over the legislation could then drag on for several weeks.

Even if the bill becomes law, Congress will not have cleared away all the obstacles to construction. In Nebraska, which is on the pipeline’s proposed path, the state's supreme court has yet to rule on the constitutionality of a state law that allowed the government to set aside residents' private property for pipeline construction. If the court rules against the state and in favor of local landowners, it could throw a major roadblock in front of the current plan.