Within the last 24 hours, the President-elect has had phone conversations with 2012 Republican nominee Mitt Romney as well as primary rivals Ohio Gov. John Kasich and former Florida Gov. Jeb Bush, CNN has learned.
Each call was described to CNN as a cordial message of congratulations.
Trump confirmed the calls in a series of tweets on Sunday morning, calling calls from Romney and the Bushes "very nice!"
Months earlier, the three men comprised some of Trump's most outspoken Republican opponents, and Trump attacked each of them during the primary and during the general election.
The exchanges seemed personal as Trump endorsed Romney in 2012, but the former Massachusetts governor failed to return the favor. And after Romney repeatedly criticized Trump for his rhetoric toward minorities, Trump ended up doing better with black and Latino voters than the 2012 candidate.
Bush, once a front-runner in the primary, was often called "low energy" by Trump and criticized for not honoring his pledge to support the eventual nominee. Kristy Campbell, a spokeswoman for Bush, said the former Florida governor spoke with Trump Friday afternoon and wished him well in the future.
And Kasich boycotted the Republican National Convention where Trump clinched the nomination even though it was in his home state. In the end, Trump won Ohio in the election. At the White House on Thursday to accompany the world champion Cleveland Cavaliers, Kasich said he was praying for Trump and the nation.
Other former Trump rivals have offered congratulations.
On Thursday, Texas Sen. Ted Cruz spoke with Trump and Vice President-elect Mike Pence, and former Presidents George H.W. Bush and George W. Bush called Trump to congratulate him
on Wednesday. Former President Bill Clinton has also spoken with Trump, and Democratic nominee Hillary Clinton conceded to Trump early Wednesday morning.