Congressional Republicans have been pushing for approval of the pipeline for years. Obama has resisted because of environmental concerns.
The Republican-led House has repeatedly passed legislation approving the pipeline. But the bills have died in the Democratic-controlled Senate.
Republicans, who now take control of the Senate, said approving the pipeline is the first issue on the agenda.
McConnell said the pipeline would create thousands of jobs.
But as crude oil prices drop around the globe, some have questioned whether the pipeline still makes economic sense. Global crude prices hovered below $60 Tuesday, their lowest price in five years.
But Democrats have already stated they will do whatever necessary to stop the pipeline, including fully backing a presidential veto.
Democrat Senator Chuck Schumer said Democrats have enough votes to support the president if he vetoes a bill to begin construction on the Keystone XL pipeline (watch the video below courtesy CBS):
With files from Associated Press