OKLAHOMA CITY _ Republican John McCain swept to an easy victory over Democrat Barack Obama in Oklahoma on Tuesday, keeping the state in the GOP for the 11th straight presidential election.

Neither McCain nor Democratic challenger Barack Obama campaigned in Oklahoma after their party's national conventions and instead spent their time in battleground states.

The call was based on an analysis of voter interviews, conducted for The Associated Press by Edison Media Research and Mitofsky International.

McCain was expected to score a double digit win over Obama, who finished far behind Hillary Clinton in the state's presidential primary in February.

Republican officials were predicting that McCain would get his largest percentage victory in either in Oklahoma or Utah.

That might seem curious, considering Oklahoma Democrats still outnumber Republicans in voter registration — 1.1 million to about 860,000.

But Oklahoma has not voted Democratic in a presidential election since Lyndon Johnson of neighboring Texas won in 1964. The state has been trending to the GOP for decades.

Rural Democrats in parts of southern Oklahoma are conservative and traditionally vote Republican in federal elections.

The state's two senators are Republican, as well as four of the state's members of Congress. The state House went to the GOP in 2004 and Republicans predicted they would take over the state Senate this year.

Democratic officials in Oklahoma conceded the race to McCain, who visited the state only once this year for a fundraiser after speaking to the state House in 2007.

However, state Democratic Chairman Ivan Holmes said enthusiasm of young voters should allow Obama to beat John Kerry's dismal 35 percent showing in 2004.

Democratic Gov. Brad Henry endorsed Obama in April, but Democratic U.S. Rep. Dan Boren did not, although he said he would vote for the Illinois senator.

Holmes said race could be an issue with the state's older voters and Obama was expected to make his best showing in urban areas. The state has a black population of only about 8 percent.

In the Democratic primary in February, Obama got only 31 percent of the vote against Clinton, who got 55 percent and racked up big margins in rural counties.

State Republican Chairman Gary Jones said rural opposition to Obama was more about "him being so liberal" than it was about his race.

George McGovern had the worst showing of a Democratic presidential candidate in 1972, getting only 24 percent of the vote. Nationally, McGovern lost 2-1 to Republican Richard Nixon.

Jimmy Carter's 13 percent margin of defeat against Republican Gerald Ford in 1976 is the best performance by a Democrat in Oklahoma since Lyndon Johnson captured the state's electoral votes 44 years ago.

Democrats registered more voters across the nation this year, but Republicans increased their ranks by about 2,000 in Oklahoma.

Copyright 2008 The Associated Press.