Facing Republican resistance to extending a payroll tax holiday, House Speaker John A. Boehner is considering sweetening the package for his party members with legislation that would advance the controversial Keystone XL pipeline.

Failure by Congress to approve an extension of the payroll tax break before it expires at the end of the year would result in an average $1,000 annual tax hike on 160 million American workers.

The prospect of that politically unpopular outcome has led GOP leaders to coalesce around President Obama’s proposal to continue the tax break for 2012.