(CNN) -- A new Republican ad appears to suggest that Barack Obama has al but won the presidential race, an argument several vulnerable Senate Republicans may have to reluctantly embrace with only days until Election Day, an expert in campaign advertising said.

Some Republicans are already planning on a Barack Obama presidency.

Aimed at Kay Hagan, Sen. Elizabeth Dole's surprisingly strong Democratic challenger in North Carolina, the 30-second spot from the National Republican Senatorial Committee warns voters against Democrats holding the White House and Congress, and flatly states that if Hagan wins, the party will "get a blank check."

"These liberals want complete control of government in a time of crisis, all branches of government," the ad's narrator states. "No check and balances, no debate, no independence. That's the truth behind Kay Hagan. If she wins, they get a blank check."

Committee Online Communications Director John Randall denied that the ad is suggesting that GOP nominee John McCain will lose out on the White House.

"The NRSC is not conceding a Barack Obama presidency," he said. "Fiscally irresponsible liberals like Kay Hagan are not the answer in these tough economic times and would only make things worse. Our ad was intended to highlight Hagan's many failings in light of the Democrats' promise to close debate should they control the executive and legislative branches of the federal government."

But with polls warning of a GOP bloodbath November 4, vulnerable senators in red states may have no other option but to suggest that Obama will capture the White House and warn that the Illinois senator needs to be checked by Senate Republicans. Watch more on the fight for battleground states »

"They are basically painting the picture that the presidential race is over," said Evan Tracey of Campaign Media Analysis Group, CNN's consultant on ad spending. "Overall, people prefer divided government. This is that divided government argument: 'Don't hand sole control over to one party.' "