WASHINGTON -- A quiet transformation is taking place in the Republican Party, which has begun to embrace openly gay candidates – and among gay Republicans, who now feel more comfortable speaking out in a party that may have accepted them but didn’t always show it.

While differences still exist, the party is on the cusp of a generational shift in which the longtime foes of gay rights are replaced by younger party leaders who are more accepting.

“It’s an exponential change from a few years ago,” said former Republican Rep. Jim Kolbe. “It’s happening, and it’s going to continue to happen.”

Kolbe, who represented the southeast corner of Arizona from 1985 to 2007, was one of only two openly gay Republicans ever to serve in Congress.

There are issues on which many gay Republicans differ with their party, not the least of which is same-sex marriage. Republican presidential candidate Mitt Romney and other party leaders oppose it, and that stance is embedded in the party’s platform. While they may have welcomed President Barack Obama’s support of same-sex marriage last week, on other issues – such as taxes, regulation and the size of government – gay Republicans are as steadfast as any other party member.

There are only four openly gay members of Congress now, all Democrats. But that could change this year.

“You’ll elect at least one gay Republican for Congress this year,” Kolbe said.

It might be Richard Tisei, a former Massachusetts state senator, who’s campaigning on what he describes as the number one issue for gay voters and everyone else in the state’s 6th Congressional District, north of Boston.

“In general, the campaign I’m running on is based on the economy,” he said.

Tisei does support same-sex marriage, and he said party leaders knew that from the beginning of his campaign for Congress.

“I don’t agree with the party platform, but that doesn’t mean I’m not a good Republican,” Tisei said.

The National Republican Congressional Committee has designated Tisei as a “Young Gun,” meaning he’s on the national party’s radar and can expect to get more resources for his campaign. Committee Chairman Rep. Pete Sessions of Texas said Tisei “has met organizational and fundraising benchmarks and has established himself as a strong contender.”

Tisei, who was a Massachusetts legislator for 26 years and a candidate for lieutenant governor, said the fact that he was openly gay had been no barrier to his rise.

“I’m very comfortable with who I am and what I believe in,” he said. “When people view me, they view me in the context of what I’ve accomplished. That’s the way it should be.”

Donald Haider-Markel, a political science professor at the University of Kansas and the author of “Out and Running: Gay and Lesbian Candidates, Elections and Policy Representation,” said there’d been a shift in the Republican Party in the past decade.

“The party overall has been more open to gays and lesbians,” he said. “And gay and lesbian candidates have been more supported.”

There are awkward moments. Earlier this month, for example, Romney hired Richard Grenell, an openly gay foreign-affairs expert who’d worked for former United Nations Ambassador John Bolton. But the Romney campaign was caught off guard by the backlash from social conservatives, who protested Grenell’s outspoken support for same-sex marriage.