Dole said he would attend the Republican National Convention in Cleveland. “We must unite as a party to defeat Hillary Clinton,” he said in the statement.
The announcement comes after former presidential candidate Jeb Bush and Sen. Lindsey Graham on Friday said they would not vote for Trump in November and would sit the presidential election out.
And on Thursday, Republican House Speaker Paul Ryan said he was “not ready” to endorse Trump but hoped at some point to be comfortable enough to do so.
Speaking to a crowd in Omaha earlier Friday, Trump said Republicans are “supposed to be coming together” and he doesn’t know why House Speaker Paul Ryan declined to immediately endorse him.
“Paul Ryan, I don’t know what happened,” Trump told the crowd of around 1,500 inside an airport hangar. “I don’t know. He called me two, three weeks ago - it was a very nice conversation. He was congratulating me.”
Both Trump and Ryan are set to meet together next week in Washington, D.C.
Former Texas Gov. Rick Perry, who once called Trump’s candidacy “a cancer on conservatism,” endorsed Trump Thursday.
“He said I’m a cancer on the Republican Party — that’s the bad news,” Trump said Friday. “Let me tell you the good news — yesterday, he endorsed me. And I like him. I do like him. I forgot about the one hour where he went wild.”
Nebraska Gov. Pete Ricketts introduced and publicly endorsed Trump at Friday’s event. Ricketts earlier this week was expected to endorse Ted Cruz before he suspended his presidential bid.
“Politics is won by the people who show up,” Rickets said, adding: “We’re all here because we know we need to take back our country.”
But the politics surrounding Ricketts endorsement, and Trump’s direct references to it on Friday, were at the center of a week that has clanked together anti-Trump forces in the Republican Party with those acquiescing to the pending Trump nomination.
Ricketts’ extended family, including his brother Tom Ricketts, the owner of the Chicago Cubs, has injected millions into Our Principles Pac, the super PAC founded by Republican strategist Katie Packer, to help block Trump’s path to the presidency.
“I love Pete,” Trump addressed the crowd with Ricketts standing off stage. “But I think his brother doesn’t like me as much as he does. But I like him, so much I’m starting to like the Chicago Cubs again.”
Moments later, talking about his Indiana primary victory that all but sealed up his nomination, Trump then called the anti-Trump efforts in the Hoosier state the “last stand for Pete’s family.”
This story originally appeared on NBCNews.com.