CHICAGO — Despite a months-long effort to unseat him by influential members of his own party, Illinois Gov. Pat Quinn emerged as Democrats' presumed standard bearer to keep the office next year after former White House chief of staff William Daley abruptly dropped his primary challenge.

Daley, who insists he could have won but didn't have the heart for a prolonged battle to fix the state's monumental problems, got in some parting shots by predicting the incumbent will lose next year to a Republican.

There was no usual call Tuesday for endorsing the likely Democratic nominee or for party unity to retain the governor's office or solve the state's fiscal troubles. Instead he referred back to his previous criticisms of his fellow Chicago Democrat's leadership and how Quinn's best attributes are being a nice guy and loyal White Sox fan.

"It wasn't a great summer he had," Daley said, noting Illinois' worst-in-the-nation state pension crisis and an extravagant renovation at the state Capitol that included nearly $700,000 copper-plated doors.

But longtime political observers say Daley's departure is another sign of the power of incumbency and just how formidable a rival Quinn could be in 2014, even with widespread concerns about his handling of the pension mess and Illinois having the nation's second-highest unemployment.

"Whether people are fond of him or not, he's the governor and he's going to be governor for another year and a half," said two-term former Republican Gov. Jim Edgar. "That's a lot of leverage."

Quinn is a former lieutenant governor who ascended to the top job when now-imprisoned former Gov. Rod Blagojevich was ousted from office. He survived a tough primary in 2010, going on to defeat his Republican rival by a razor-thin margin in the Democrat-dominated state.

Some members of both major parties saw him as an easy target in 2014. The state's popular attorney general contemplated a primary challenge but decided to run for re-election after her father — the longtime Democratic party chairman and House speaker — said he wouldn't step down. A state senator who now holds President Barack Obama's former seat also considered a bid but chose not to run.

Daley's about-face now leaves an anti-violence activist who has raised little money and hasn't filed paperwork with state elections officials as the only known Democrat still planning a primary challenge. Four Republicans are vying for their party's nomination.

Quinn's campaign issued a statement late Monday saying they are confident that come Election Day, voters "will recognize the difficult and important work the governor has accomplished on their behalf."

Daley dismissed any notion Tuesday that he couldn't have defeated Quinn. He said he believed he could continue to raise the funds and had the statewide support, including in downstate Illinois where the family name of the son and brother of two longtime Chicago mayors may not play well.

"As a part of a family that has public service in its blood and a family of which I am extremely proud, I've always been motivated as each of them to serve," he told reporters as his voice crackled. "This race was a very doable race for me."

He was less clear about his reasons for dropping out. He only said there was an "enormity" to being a candidate he didn't realize previously and that Illinois needs a strong leader to help solve its monstrous financial problems — including the nation's worst-funded pension system.

"I've lost sleep ... and struggling over the last couple weeks over whether or not what's needed I can provide over a long period," he said. "It's not about a campaign of six months or 14 months. It really is about a minimum of five to nine years to begin to straighten out this state."

But in recent weeks Quinn, who has long portrayed himself as an outsider and underdog, secured some key backing. The Cook County Democratic Party — once the organization of Daley's father, the late Chicago Mayor Richard Daley — endorsed Quinn, as did Democratic party chairmen in 79 of the state's 102 counties. Quinn also has shored up support in the black community, and Daley didn't dispute a comment that he was likely to be the loser when Illinois Democratic leaders meet in Springfield this weekend to discuss slating party candidates for statewide office.

State Rep. Brandon Phelps, a Democrat from southern Illinois, said he didn't know how Daley's name would carry in his territory.

"There are a lot of people who do not know Bill Daley, they just think it's a Chicago name. I don't know if it would have played down south at all," Phelps said.

Daley and Quinn also had begun providing glimpses of the attacks they planned to level at one another. While Daley ripped Quinn's leadership, the governor called Daley a "millionaire banker" who "helped drive the American economy into a ditch and created the Great Recession." Quinn's campaign also was expected to repeat an assertion by the author of a book on the 2008 presidential campaign that Daley's tenure in Obama's White House was "a walking disaster."

Daley, 65, said he would audit the campaign funds he has raised — roughly $800,000 by the end of June — and return donations.

The four Republicans in the race are state Treasurer Dan Rutherford, state Sens. Bill Brady and Kirk Dillard and venture capitalist Bruce Rauner. Quinn's lone remaining opponent for the Democratic nomination, Tio Hardiman, said he is staying in the race, but acknowledged that he lacks the governor's name recognition and resources.