INSTANT VIEW: McCain and Clinton win key White House contests

WASHINGTON (Reuters) - Republican John McCain and Democrat Hillary Clinton won presidential nominating contests in South Carolina and Nevada respectively on Saturday, gaining strength in an unpredictable White House race where no candidate has been able to sustain momentum.

Following is some reaction:

SCOTT KEETER, PEW RESEARCH CENTER:

"The results today in South Carolina suggest that (Republican candidate Mike) Huckabee is having trouble extending his appeal beyond the evangelicals. He won no major demographic groups among non-evangelicals. Unless he can broaden his appeal, he'll have trouble in states with fewer evangelicals."

SCOTT REED, REPUBLICAN STRATEGIST:

"There is a clear path now for McCain to be the nominee of the Republican Party, and he's got momentum and that is the biggest asset you can have in national politics."

DAVID BEASLEY, FORMER SOUTH CAROLINA GOVERNOR AND HUCKABEE

ADVISER:

"It was a Huckabee victory for him to come so close, given all the odds that were against him."

JOHN "CHIP" SALTSMAN, HUCKABEE'S NATIONAL CAMPAIGN

MANAGER:

"We came up a little short. We're going to move on to tomorrow."

DAVID BONIOR, CAMPAIGN MANAGER FOR DEMOCRATIC PRESIDENTIAL

CANDIDATE JOHN EDWARDS:

"The race to the nomination is a marathon and not a sprint, and we're committed to making sure the voices of all the voters in the remaining 47 states are heard ... Saving the middle class is going to be an epic battle, and that's a fight John Edwards is ready for."

(For more about the U.S. political campaign, visit Reuters "Tales from the Trail: 2008" online at blogs.reuters.com/trail08/)