U.S. senior citizens are likely to cast their ballots in favor of Republican challenger Mitt Romney rather than President Barack Obama in November, continuing a shift among older Americans toward alignment with the Republican Party, experts said.

In a Pew Research report released last month, half of voters over age 65 favored Romney, while 44 percent supported Obama. In a May Fox poll of registered voters, Romney leads Obama by 52-38 among those aged 65 and over.

"Obama will almost certainly lose the senior vote," said John Fortier, director of the democracy project at the Bipartisan Policy Center. "Today, the senior vote is the most Republican vote of all of the age cohorts."

That was not always the case, as the World War II generation seniors tended to be strong Democrats. But in the past decade, the senior vote, which includes many born in the post-war years, has trended strongly Republican.

Pew called Americans aged 65 to 83 -- the vast majority of older Americans -- the "silent" generation, which replaced the so- called "greatest generation" -- those who came of age in World War II and who were more reliable Democratic voters when they constituted the bulk of the senior vote.

The silent, however, increasingly call themselves conservative and hold the most consistently right-leaning views about government, social issues and America's place in the world.

"Today, an overwhelming majority of Silents are either angry or frustrated with government," said the Pew report. "They are the generation that is most strongly disapproving of Barack Obama, for whom a majority did not vote."

Silents also are the most politically energized generation, as they demonstrated in the 2010 midterms when Republicans swept the House of Representatives. Fifty-nine percent of seniors voted Republican.

Dan Mahaffee, an analyst with the Center for the Study of the Presidency and Congress, noted that seniors make up a significant portion of the population in key swing states -- 17.3 percent in Florida, 15.4 percent in Pennsylvania, 14.9 percent in Iowa, 14.1 percent in Ohio, and 14 percent in Missouri.

Like virtually every other group, the economy trumps all other issues in the minds of seniors, as many are retired and living on fixed incomes -- a mix of personal savings, social security and pensions.

"The economy is the top issue for all voters including seniors. Nothing else comes close," said Karlyn Bowman, senior fellow at the American Enterprise Institute.

Bowman noted that seniors turn out to vote more than younger voters, which could prove an advantage for Republicans in November, as the Obama camp may have trouble in getting disappointed supporters off the couch and into the voting booths.

Before becoming Republican, seniors have over the past few decades swung between supporting both parties. According to exit polls, they looked Republican from 1972 to 1988, when they split fairly evenly. They voted for former president Bill Clinton in both 1992 and 1996. In 2000, this group voted for Bush, and in 2004 for Kerry.

On social issues, seniors are generally more conservative than other age groups, especially on issues such as gay marriage and gays in the military, Fortier said.

And compared with the youngest age group, between 18 and 29, the older age groups are much more skeptical of the role of government, he added.

Still, while silent generation voters say they are solidly behind Obama's Republican challengers, there are some signs of potential opportunity for the Democrats.

Silents cite Social Security as often as they name jobs as their top voting issue. And while seniors tend to favor the Republican Party on most issues, they are as likely to favor the Democrats on social security, Pew said.