Florida Gov. Charlie Crist, Louisiana Gov. Bobby Jindal and former Massachusetts Gov. Mitt Romney, a McCain rival in the primary, were invited to a weekend gathering at the senator's place in Sedona.
They were among the estimated two dozen people - including some 10 couples - invited. McCain often hosts friends and political acquaintances at his compound.
The Republican nominee-in-waiting said more than a month ago that he was in the "embryonic stages" of selecting a running mate for the fall campaign, but neither he nor aides have disclosed additional information in the weeks since.
It will be the first visit to Sedona, Ariz., for all three.
Romney dropped out of the race in February after it became apparent it would be near impossible to topple McCain in the convention delegate race. He endorsed McCain a week later and pledged to help him win the nomination.
Since then, McCain has praised Romney repeatedly as someone who is certain to continue playing a large role in the GOP. Romney, for his part, has suggested that he'd accept a vice presidential slot, though some Republicans privately speculate that he's looking ahead to a possible repeat run in 2012.
Crist, 51, provided a major boost to McCain before Florida's Jan. 29 primary with a well-timed endorsement.
Elected governor in 2006, he has been seen as a moderate Republican. He has championed efforts to curb climate change, and former President Clinton praised him for his efforts to restore voting rights of felons who have completed their sentences. Crist also pushed for a law that requires a paper trail in state elections.
Jindal, 36, son of Indian immigrants, was elected governor of Louisiana in October 2007, three years after being elected to the House, where he was credited with playing an important role as his state recovered from Hurricanes Katrina and Rita.
Before serving in Congress, he was secretary of Louisiana's health department, and was an assistant secretary in the U.S.
Department of Health and Human Services.
Among other guests expected were Sens. Joe Lieberman, an independent from Connecticut, and Lindsey Graham, R-S.C., close confidantes of McCain.
The New York Times first reported that Crist, Jindal and Romney would visit the ranch.
