By Steve Holland
WASHINGTON (Reuters) - Former Republican presidential nominee Mitt Romney will run for a U.S. Senate seat in Utah, a source familiar with Romney's plans said on Wednesday.
Romney said later he would not make any announcement on Thursday, as had been expected, because of a deadly school shooting in Florida.
"Out of respect for the victims and their families, I will not be making an announcement tomorrow about the Senate race," he said in a Twitter post.
A 19-year-old gunman returned to a Florida high school where he had once been expelled for disciplinary reasons and opened fire with an assault-style rifle on Wednesday, killing 17 people before he was arrested, authorities said.
Romney will pledge to "bring Utah values to Washington, D.C." and plans to run a very Utah-centric campaign, the source said.
Romney was the 2012 Republican presidential nominee, losing to Democratic President Barack Obama in the election that year.
In the 2016 campaign, Romney decided not to seek the nomination. When Donald Trump's candidacy gained strength, Romney urged Republicans not to support him, an effort that fizzled as the New York real estate magnate went on to win the nomination and the November election.
Trump had considered Romney for the position of U.S. secretary of state, but picked oil executive Rex Tillerson instead.
The president had urged incumbent Republican Senator Orrin Hatch to run for re-election in Utah, but Hatch opted not to do so, opening the door to Romney's candidacy.
Romney, a wealthy former governor of Massachusetts, has homes in Utah and California.
(Additional reporting by Eric Walsh in Washington; Writing by Susan Heavey; Editing by Jonathan Oatis and Peter Cooney)