WASHINGTON — TransCanada said Monday that it would reapply for a permit to build the Keystone XL pipeline from Canadian oil sands formations in Alberta to refineries on the Gulf of Mexico, assuring that the fiercely contested project will remain a source of political heat throughout the presidential campaign.

The company also said it would seek immediate permission to move ahead with the southernmost portion of the project, from Cushing, Okla., to the gulf, in the hope that that part of the pipeline could be in service by the end of 2013. As a standalone project, the company said, the Gulf Coast portion of the pipeline would cost $2.3 billion and create about 4,000 construction and support jobs.

In January, President Obama rejected the company’s previous application to build the full pipeline, saying a Congressional mandate that he decide on the project by mid-February did not allow adequate time to complete environmental reviews. He said his action was not a final judgment on the project and invited the company to move quickly on the southern part of the 1,700-mile pipeline, which would transport only domestic oil. That part would not cross any international borders and thus would not require special approval from the State Department.

Republicans in Congress and on the campaign trail have harshly criticized the president’s decision to block the pipeline, saying it forfeited American jobs and increased the country’s dependence on imported oil.