Recall when analysts declared Governor Joe Manchin the winner of the special election to replace Robert Byrd even before the West Virginia legislature created it?  With an approval rating in the mid-70s, Manchin was so unbeatable that leading Republicans were advised to keep their powder dry and hold onto their current offices rather than challenge for the seat.  Instead, it fell to a man who tried to unseat Robert Byrd to come again out of the private sector — and find out that perhaps Manchin isn’t as invincible as people thought, according to Rasmussen’s first survey of the race (via John McCormack):

Now that state legislators have officially approved a special Senate election this November to replace the late Robert Byrd, the state’s Democratic governor still earns majority support to win the job.

The latest Rasmussen Reports statewide telephone survey of Likely Voters shows Governor Joe Manchin picking up 51% of the vote when matched against businessman John Raese, who picks up 35%. Five percent (5%) would prefer a different candidate and another nine percent (9%) are undecided.

Though five candidates have filed for the Republican nomination, Raese is the most notable. He ran a close race for Senate in 1984, and later challenged Byrd for his seat in 2006. He lost handily.

There’s no doubt that Manchin has built a large store of favorability in West Virginia.   He has a 74/24 rating for a powerful +50.  Among independents, it’s almost as good at 64/29, a +35.  He also has a 71% job approval rating, and 63% among independents. Normally, that would be a sign of political invincibility.

However, that doesn’t translate to sure-fire success in 2010 for Manchin.  For a popular sitting governor to only get 51% of the vote while having a 74% positive rating is a sign that other considerations have come into play.  And actually, the partisan splits are telling.  Raese actually beats Manchin among independents, 42/30, even though 35% of unaffiliated voters don’t know Raese well enough to have an opinion of him.  Only 7% of independents don’t have an opinion of Manchin, which means a lot of independents who do have an opinion don’t want to vote for him.

The big problem for Manchin is having the Republicans come home.  Raese at the moment gets 56% of the GOP vote, while Manchin gets 29%.  That will almost certainly change (assuming Raese wins the primary) when the Republicans underscore that a vote for Manchin means a vote for Harry Reid to run the Senate, or even worse, Chuck Schumer if Reid loses in Nevada.  Meanwhile Raese manages to get 18% of the Democratic vote, and that may change for the same reason in a coal state like West Virginia, where the mining industry has come under attack by the EPA.

The issues also strongly favor Republicans.  Almost two-thirds want ObamaCare repealed (64%).  Only 6% think the economy is good or excellent, and 63% believe it to be getting worse while only 18% think it’s getting better.  Barack Obama has an approval rating in the state among likely voters of 32/67, an abysmal figure.

The big question here is what a better-positioned Republican could have done against Manchin.  In this environment, a 51% rating for Manchin doesn’t look invincible at all, and Raese has a shot at beating the popular governor by focusing on those issues and Democratic failure on them.