Former Sen. George McGovern, an early supporter of Hillary Clinton, 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.

"She and President Clinton will be my friends as long as I live," McGovern told The Associated Press.

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.

Asked whether McGovern's statements might take some of the bloom off Clinton's visit, Rick Hauffe, executive director of the state Democratic Party, said, "I would say that the results of last night had a lot more impact on that bloom than his statement."

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

But Obama has won the nomination "by any practical test" and is very close to a majority of the pledged delegates, said McGovern, 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. "I now think the time has come for her to fold her tent and get the party unified, if that's possible."

The nomination fight will not go to the national convention, McGovern said. The Democratic superdelegates are evenly divided, and Obama has almost a majority of the pledged delegates, he said. "There's no way mathematically that Hillary could get the nomination."

McGovern said the Democratic nomination process has energized many potential voters but that he sees no point in continuing to spend money and energy on it anymore.

As for Obama, "He's waged a wonderful campaign. I'm very inspired by the guy."

McGovern's decision "has got to be pretty deflating to Clinton," Hauffe said, adding that he is certain McGovern agonized over it.

"George makes these kinds of decisions based on reason," said Hauffe. "I've never heard him say anything that wasn't a really reasoned statement. So he's looking at what's good for the party and ultimately what's good for the nation."

Clinton has more primaries ahead of her, Hauffe said. "If she continues the campaign, she's got some major tests in West Virginia and the other larger states that are still holding primaries," he said. "She's got to really think this thing out."

As a party leader of a state with a late primary, Hauffe said he has mixed emotions about the development. "Here we are on the cusp of having a real showdown in South Dakota."

He said plans have been in the works for a joint candidate appearance on May 24 in Sioux Falls. Asked if it's still on, Hauffe said, "It's on the drawing board; it's written in pencil."