By TOM RAUM, Associated Press
Dropping out is hard to do. It's been especially hard for Newt Gingrich and Ron Paul.
Mitt Romney is claiming victory after his Tuesday sweep of five more GOP primaries. Few disagree.
He has an insurmountable lead. He's expected to clinch the nomination next month. RNC Chairman Reince Priebus on Wednesday anointed him "our party's presumptive nominee."
After remaining in the race against all odds, Gingrich will formally end his campaign next Tuesday and likely endorse Romney, advisers to the former House speaker told The Associated Press on Wednesday.
Earlier, Gingrich acknowledged Romney would win but quizzically suggested he'd keep campaigning as a "citizen."
Paul, a congressman from Texas, says he'll stay until all delegates are counted, suggesting it isn't over until it's over.
Former Sen. Rick Santorum, R-Pa., who exited two weeks ago, said Tuesday night the former Massachusetts governor "is going to be the nominee" and that he would "support the nominee." That wasn't quite a formal endorsement, but the closest he's come.
Santorum said he'll sit down with Romney representatives soon.
All the other former GOP rivals have endorsed Romney.
It's never easy for presidential candidates to throw in the towel. They've invested so much time and energy into the pursuit.
That was certainly true last time, when then-Sen. Hillary Rodham Clinton remained in the Democratic primary long after she had any hope of winning.
Obama mathematically clinched the nomination on June 3, 2008, and Clinton endorsed him five days later. But their first joint appearance was not until June 27 at a carefully choreographed rally in Unity, NH.
Only one loser has publicly voiced what many failed presidential contenders have probably thought. After finishing second to Jimmy Carter in seven 1976 primaries, Rep. Morris K. Udall of Arizona famously declared, "The people have spoken, the bastards."
Follow Tom Raum on Twitter: http://www.twitter.com/tomraum. For more AP political coverage, look for the 2012 Presidential Race in AP Mobile's Big Stories section. Also follow https://twitter.com/APCampaign and AP journalists covering the campaign: https://twitter.com/AP/ap-campaign-2012.