"While it's harder for me to step back than step forward, today I step back and withdraw from the race," Cuomo said at a Tuesday afternoon news conference attended by family and friends, including his father, former Gov. Mario Cuomo, former President Bill Clinton and Rep. Charles Rangel.
Cuomo encouraged all his supporters to follow him in backing McCall, saying it was time for party unity.
"We need healing now, maybe more than ever before," said Cuomo. "I'm not going to start dividing now."
Cuomo's surprising withdrawal came one week before the Sept. 10 Democratic primary, clearing the way for McCall to challenge two-term incumbent Gov. George Pataki — the Republican who vanquished the elder Cuomo eight years ago.
McCall held an afternoon press conference where he thanked Cuomo and his running mate. "I appreciate and I welcome Andrew Cuomo's support and his decision to join with Dennis Mehiel and me," he said. Mehiel is the McCall's pick for lieutenant governor.
McCall said he not spoken with Cuomo since his opponent's announcement earlier Tuesday. He said he planned to meet with Cuomo to discuss what, if any, role Cuomo would have in McCall's campaign against Pataki.
Recent polls put McCall, 66, more than 20 percentage points ahead of Cuomo, 44, among likely Democratic voters, leading to talks that began Sunday about presenting a unified Democratic front.
Mr. Clinton, who advised Cuomo about whether to proceed with the campaign, told the former HUD secretary's family that "today is a day when you should be very proud of Andrew."
While officially neutral, there have been signs in recent weeks that Mr. Clinton and his wife, New York Sen. Hillary Rodham Clinton, have been leaning toward the comptroller.
On Friday, the Clintons were at the State Fair in Syracuse at the same time as Cuomo. The trio didn't even manage a photograph together. On Monday, Sen. Clinton had McCall marching by her side in the West Indian American Day parade in New York City.
"I'm shocked," former New York Mayor Ed Koch said when he learned of Cuomo's decision. "Obviously, it's got to be a very sad day for him and his father and wife in particular. ... We certainly have not heard the last from Andrew Cuomo. He will run again."
Word of the withdrawal by Cuomo came as an independent statewide poll reported that McCall's lead over Cuomo continued to widen.
The poll, from the Quinnipiac University Polling Institute, had McCall, the only black candidate ever elected to statewide office in New York, leading Cuomo, 47 percent to 25 percent, among the likely Democratic voters.
When those leaning toward one candidate or another were factored in, McCall led Cuomo, 53 percent to 31 percent. The telephone poll of 452 likely Democratic primary voters was conducted Aug. 26-Sept. 1 and had a margin of error of plus or minus 5 percentage points.
Cuomo, 44, entered the governor's race early last year with a lead in the polls. While he had served as his father's top political adviser for years, the race against McCall was his first as a candidate.
There were missteps along the way — the most visible in April when he complained that Pataki had ceded post-Sept. 11 leadership to then-Mayor Rudolph Giuliani. Cuomo said the governor had merely "held the leader's coat."
"Andrew Cuomo's troubles began the minute he engaged in negative personal attacks against Gov. Pataki, and he never recovered," Pataki campaign manager Adam Stoll said. Cuomo was roundly criticized for the remarks; even his father later said it had been a political mistake.
Cuomo also stunned Democrats last May when he turned his back on state party leaders by dropping out of the state convention on its opening day. When it appeared he would not receive enough delegate votes to gain a spot on the primary election ballot, Cuomo opted instead to collect signatures from voters statewide.
Meanwhile, McCall, 66, ran a fairly steady campaign focusing on his rise out of poverty, a lengthy resume that included a stint as a deputy ambassador to the United Nations and as a Citibank vice president, and his promise to improve education in the state.