Sen. Kelly Ayotte (R-N.H.) on Thursday urged Senate Democrats to allow a separate, majority-rule vote on a measure attached to the payroll tax holiday bill that is meant to force the administration to approve the Keystone oil sands pipeline.

President Obama has threatened to veto the House-passed payroll tax bill, and one of his objections is to the Keystone language.

The stalemate between the House and Senate has caught up the payroll bill and a $1 trillion omnibus spending package.

Ayotte said there were enough Democrats who support building Keystone that it would pass the Senate if it only needed 51 votes, and not the 60 generally required to clear procedural hurdles.

"I also think one thing we can do is if the Democrats don't want the Keystone pipeline in it, why not break up the package and allow a vote on each part of it, including the Keystone pipeline, at a 51-vote threshold? Because I know that there are enough Democrats that it will pass," Ayotte said Thursday on Fox News. "So Harry Reid should let that vote come to the floor."

It's unclear whether there are enough votes in the Senate to reach 51. Ten House Democrats supported the GOP payroll bill.

Democrats and environmental groups have voiced opposition to the pipeline.