(Cliff Owen/AP)

The battle over the Keystone XL oil pipeline is far from over, Senate Republicans said Saturday.

As Congress is poised to send to President Obama a payroll tax cut package including a measure that would speed up a decision on the trans-continental pipeline, Republicans maintained that a decision by the administration to deny a permit for the project would mark only the beginning of the Keystone fight.

“If the president denies the American people these jobs and this source of energy from our ally, Canada, it will not be the last time he sees this bill,” said a Senate Republican leadership aide who spoke anonymously in order to candidly discuss legislative strategy. “Republicans will continue fighting for this bipartisan job-creation (measure), even if the president wants to stand between the unemployed and good American jobs.”

Several Republican senators exiting the Capitol after Saturday’s votes – the last of the 112th Congress’s first session – also said that they expected that the GOP will continue its push for the Keystone pipeline in February, the next deadline for Congress to act on extending the payroll tax cut.

“I would guess that the Keystone issue will come up again,” Sen. Rob Portman (R-Ohio) told reporters Saturday afternoon. “I think there are the votes in the Senate to pass a Keystone bill that goes even further than this language.”

Portman added that “it seems like it’s an issue that once people understand it, it’d be difficult for the administration to deny without Congress acting again. So I think it comes back up.”

President Obama, who had previously said he would reject any effort to tie Keystone to a payroll tax cut extension, made no mention of the pipeline in brief remarks at the White House following Saturday’s votes.

Senate Democrats, meanwhile, insisted that the pipeline argument is one in which they believe they have the upper hand.

“The point is the average person is not at all focused on the pipeline,” Sen. Charles Schumer (D-N.Y.) told reporters. “It’s total inside baseball.”

Schumer, who heads Senate Democrats’ messaging shop, added that Congress’ leverage in the pipeline debate is limited since the final say on the matter rests with the administration.

“We feel as though we’re giving them the sleeve off a vest,” he said of including the pipeline provision in the final payroll deal. “The bottom line is that Secretary of State Clinton has said that if they rush the process, they’re going to end the pipeline. So, it doesn’t make much sense. And the president is totally on board with that strategy.”

Meanwhile, some Democrats on Saturday urged the administration to deny the pipeline permit. In a letter to Obama, Rep. Peter Welch (D-Vt.) argued that the Keystone project “poses a serious threat to the environment and public health that cannot be mitigated by the benefits of the project.”

“We strongly oppose an expedited review process and urge you to reject the tar sands pipeline project because of the unnecessary and inappropriate short circuiting of the review process,” Welch wrote.

Exactly what kind of further legislation Republican lawmakers plan to introduce on the pipeline remains to be seen, but aides said Saturday that Congress would be able to continue to push the administration on Keystone if a permit is denied within the 60-day timeframe.

Sen. Richard Lugar (R-Ind.), who introduced the pipeline measure in the Senate, declined to speculate on what the GOP’s strategy might be when it comes to Keystone and the next round of the payroll tax fight.

“Well, we’ll have to have some more conversations,” he said.

This post has been updated since it was first published.