Republican Mitt Romney, strongly considering a run for a U.S. Senate seat from Utah, underwent successful treatment for prostate cancer last year, a source close to Romney said on Monday.

Romney, who lost the 2012 U.S. presidential race to Barack Obama, was treated surgically by Dr. Thomas Ahlering at UC Irvine Hospital in California and his prognosis is good, the source said. "He was successfully treated," the source added.

Romney advisers say the 70-year-old former governor of Massachusetts is weighing a run in the November congressional election for a Senate seat from Utah, a Republican-dominated state where Romney has a home.

"Last year, Gov. Mitt Romney was diagnosed with slow-growing prostate cancer. The cancer was removed surgically and found not to have spread beyond the prostate," the source said.

Romney would be seeking to succeed Republican Sen. Orrin Hatch, who has announced he will retire rather than seek re-election.

President Donald Trump had urged Hatch to run again in an apparent attempt to head off Romney, who initially opposed Trump's presidential candidacy. Trump and Romney spoke by phone last week. A White House aide said Trump wished him well.