McCain turns to November: Can he win?

By Steve Holland - Analysis

WASHINGTON (Reuters) - Now that he is the U.S. Republican presidential nominee, John McCain faces a huge challenge: How to beat recent history and win a third straight White House term for his party.

McCain scored victories in Texas, Ohio, Vermont and Rhode Island on Tuesday to complete his improbable comeback from the political graveyard last summer to become his party's standard-bearer.

The Arizona senator quickly pivoted to a November presidential election matchup against either Democrat Barack Obama or Hillary Clinton, pledging in a victory speech to make a "respectful, determined and convincing case" to Americans.

"Our campaign must be, and will be more than another tired debate of false promises, empty sound-bites, or useless arguments from the past that address not a single American's concerns for their family's security," he said.

He faces an uphill battle against either Obama or Clinton.

In the last 50 years, only once has the party in power for two terms in a row been able to win a third one, when George H.W. Bush, the current president's father, succeeded the immensely popular Ronald Reagan in the 1988 election.

And this year the call for change is plaintive: The U.S. economy is in trouble, Americans are tired of the Iraq war, and most are ready to move on from unpopular President George W. Bush.

Democrats are already trying to portray McCain as in search of a "third Bush term."