Perry had begun to call his supporters hours before his 11 a.m. press conference to tell them he was quitting.
"It was an Alamo-like effort, which will hopefully serve him well in the coming years," said a Perry fundraiser who asked not to be identified. "The people of Texas carried a lot of the weight in terms of financing Gov. Perry's campaign. But ... it was a little past time to do it, and it's still not clear why such glaring mistakes were made. And, at some level, it's a real loss for America, because he would have been a great leader, but he's clearly not a very good campaigner."
With two days to go until the South Carolina primary, Perry was polling among Republicans there at about 6 percent — the same percentage of people who said they had no opinion about whom they'd choose.
With Gingrich trailing Romney just slightly in South Carolina, Perry's endorsement has a small chance of giving him the extra boost he needs to win.
Gingrich said Wednesday that "it would be helpful" if Perry and Rick Santorum dropped out of the race before the primary. "Obviously, my pitch is, if conservatives come together, we beat Romney decisively," he said. "If conservatives are split, he might squeak through with a plurality."
Perry's exit also means that tonight's debate in South Carolina will have only four candidates: Romney, Gingrich, Ron Paul and Santorum.
Explaining his decision to leave the race, Perry said that he knows "when it's time to make a strategic retreat," and that even though he saw his candidacy as a calling, "a calling never guarantees a particular outcome."
"I've always believed the mission is greater than the man," Perry said. "As I have contemplated the future of this campaign, I have come to the conclusion that there is no viable path forward for me in the 2012 campaign."
Sullivan said the Texas governor hasn't ruled out running for reelection or a run for president in 2016.
Several of Perry's top advisers initially worked for Gingrich's presidential campaign but left in June as part of a major staff defection. Gingrich wrote the forward to Perry's book "Fed Up!"
Standing by Perry's side were his wife, Anita; his son, Griffin; and a close family friend and Navy Seal, Marcus Luttrell, and his wife. Perry kissed his wife on the lips, a rarity on the campaign trail, as he thanked her and his family for their support.
Perry returns to Texas Thursday afternoon and will consider joining Gingrich on the trail.
Some of Mitt Romney's major fundraisers have been waiting for Perry to drop out so they could start raising money from the Texas governor's wealthy friends who have been bound by allegiance to support Perry. "Now we can start today," said Fred Zeidman, a Romney fundraiser, adding that the fundraising team in Texas was "anticipating that he was going to drop out."
Bill Miller, an Austin-based lobbyist whose firm's PAC has supported Perry's campaigns, described this one as "dispirited" and divided over whether Perry should have stayed in the race. On Wednesday, the prominent conservatives Erick Erickson and Laura Ingraham wrote that Perry should drop out.
"There's probably a collective sigh of relief," said Miller, whom the Perry campaign has dismissed as a lobbyist who shifts his allegiances.