CHARLESTON, W.Va. (AP) -- U.S. Sen. Joe Manchin finds himself losing some high-profile supporters on both sides of the ideological divide ahead of West Virginia's May 8 primary, but the popular former governor on Wednesday said he's tried to remain true to his upbringing "as a commonsense, responsible Democrat."

Manchin's campaign also cited the ongoing backing of a wide-ranging coalition that includes labor unions, business groups and such special interests as the National Rifle Association.

"I am proud of the support that I have maintained and continue to have from commonsense West Virginians," Manchin told The Associated Press on Wednesday.

The Charleston Gazette, the state's largest newspaper, endorsed Manchin during the 2010 special primary and general elections. But an editorial published Wednesday leaves it up to readers whether to vote for him this time.

Manchin has failed to support some of his party's core principles, the editorial said. It noted that Manchin won't say whether he'll back President Barack Obama at the top of his party's ticket.

"Perhaps he's on course to follow Connecticut's Joe Lieberman and register as independent," the editorial said.

The editorial singles out Manchin's vote last month with Senate Republicans during their unsuccessful attempt to overturn Obama's order that most employers or their insurers cover the cost of contraceptives. The newspaper heralded the defeat of that measure in an editorial at the time.

Manchin's vote on reproductive health care issues has also cost him the longtime support of West Virginians for Life. The group says Manchin has betrayed anti-abortion voters by failing to support a complete repeal of the federal health care overhaul. It also criticizes Manchin for voting against cutting funding both for that law and Planned Parenthood.

In a February letter to that group, Manchin said the health care law includes provisions worth keeping. He also wrote that no evidence supports allegations that Planned Parenthood spends federal funds on abortions. Reminding the group that it had previously supported him as a lifelong abortion foe, Manchin cited measures he's co-sponsored in support of that position.

Manchin on Wednesday said that he's also always been "a West Virginia Democrat to my core."

"I was raised as a commonsense, responsible Democrat, and I always will be," Manchin said. "I go to work every day looking at our problems and trying to find solutions that will work for the next generation. My focus is on making our country stronger and West Virginia a better place to live."

West Virginians for Life has endorsed Sheirl Fletcher, a former two-term House of Delegates member and Republican-turned-Democrat, in the Democratic primary. The Gazette editorial said that Manchin "faces no worthy opponent in either party," and so will probably win re-election.

The winner May 8 will face John Raese, a Republican making his fourth run for the Senate. Manchin beat the Morgantown industrialist by 10 percentage points in 2010, an otherwise difficult election cycle for Democrats. Fletcher had also lost to Manchin in that year's special primary.

The 2010 special elections were prompted by the death of Sen. Robert C. Byrd that year. Manchin, 64, is now seeking a full, six-year term.