Former Sen. George McGovern, an early supporter of Hillary Rodham Clinton, has urged her to drop out of the Democratic presidential race, and endorsed her rival, Barack Obama.

After watching the returns from the North Carolina and Indiana primaries Tuesday night, McGovern said Wednesday it’s virtually impossible for Clinton to win the nomination. The 1972 Democratic presidential nominee said he had a call in to former President Clinton to tell him of the decision, adding that he remains close friends with the Clintons.

"I will hold them in affection and admiration all of my days," he said of the Clintons.

McGovern’s announcement comes a day before Clinton was scheduled to travel to South Dakota to campaign. The state holds its primary June 3 with 15 pledged delegates at stake.

McGovern said he had no regrets about endorsing Hillary Clinton months ago, even before the Iowa caucuses.

"She has run a valiant campaign. And she will remain an influential voice in the American future," he said. But, Obama has won the nomination "by any practical test" and is very close to a majority of the pledged delegates, said McGovern, who is 85. Obama moved within 200 delegates of clinching the nomination with his split decision on Tuesday of a win in North Carolina and a narrow loss in Indiana.

"It’s time to unite the Democratic Party", he said.

"Hillary, of course, will make the decision as to if and when she ends her campaign. But I hope that she reaches that decision soon so that we can concentrate on a unified party capable of winning the White House next November," he said.

McGovern is not a superdelegate, one of the prominent Democrats who has a vote at the national convention.

Barack Obama won the most delegates in Tuesday’s primaries, moving within 200 delegates of securing the Democratic nomination for president.

Obama won at least 94 delegates in the North Carolina and Indiana primaries, according to an analysis of election returns by The Associated Press. Sen. Hillary Rodham Clinton won at least 75 delegates, with 18 still to be awarded.

Sixteen of the outstanding delegates were from North Carolina and two were from Indiana.

In the overall race for the nomination, Obama led with 1,840.5 delegates, including separately chosen party and elected officials known as superdelegates. Clinton had 1,684.

Obama was 184.5 delegates shy of the 2,025 needed to secure the Democratic nomination.

There are 217 delegates at stake in the final six contests. Also, about 270 superdelegates are yet to be claimed.

Obama is on pace to reach a majority of the pledged delegates won in primaries and caucuses in two weeks, when Kentucky and Oregon vote. Obama had a 171-delegate lead among pledged delegates.

Clinton leads in superdelegate endorsements, 270.5 to 256, though Obama has been chipping away at her lead since the Super Tuesday contests on Feb. 5. Both candidates picked up a superdelegate endorsement Tuesday.

Nearly 800 superdelegates will attend the national convention. About 220 remain undecided and about 50 others will be named at state party conventions and meetings throughout the spring.

There are six primaries left in the Democrats’ epic battle for the nomination, but Tuesday’s results were decisive on their own: They offered Clinton her last, best chance to turn the tables on her rival, and she didn’t even come close.

As important, they diminished Clinton’s rationale for urging Democratic super-delegates to override his delegate lead and give the nomination to her.

"It’s bad news for Hillary Clinton, but frankly I think the game changed a long time ago," said unaligned Democratic strategist Garry South. "Barack Obama has outraised her substantially, he’s won more states, more pledged delegates, and is ahead in the popular vote. It’s obvious he’s outperformed her."

Indeed, Obama managed to outpace Clinton through a period that tested his mettle and political skills more than any other in the 15-month campaign. In a stretch that pitted Clinton’s gritty determination against Obama’s calm fortitude, the Illinois senator prevailed.