In wide-open Virginia, the presidential race's impact on the Senate contest may be tempered by the near universal name recognition of the two Senate rivals. Republican George Allen and Democrat Tim Kaine are former recent governors, and the $20 million the two have combined to spend so far makes their contest one of the nation's most expensive, according to the nonpartisan Center for Responsive Politics.
"Headwinds will largely come from the presidential, but because name identification is so high for both Governor Allen and Governor Kaine, these races will be nearly mirroring each other," said Pete Snyder, chairman of the GOP's coordinated presidential and congressional campaigns in the state.
Ticket-splitting is as much as factor in some Senate races as coattails. Democratic Sen. Joe Manchin is heading toward re-election in West Virginia and there are tight Senate races in Arizona, Indiana and North Dakota, though Romney seems certain to win all four states.
Obama is sure to win Connecticut, yet professional wrestling magnate Linda McMahon, a Republican, is running a well-financed and strong race against Democratic Rep. Chris Murphy for the seat being vacated by independent Sen. Joe Lieberman.
The presidential contest is also providing plenty of fodder for congressional campaigns — and not just in the frequent attacks that Republicans make on Obama and Democrats launch against Romney.
In a play for moderate Virginia voters, Kaine uses one TV spot to position himself between Allen and Obama. The ad states Obama's preference to block a renewal of decade-old tax cuts on income exceeding $250,000, and Allen's insistence — shared by most Republicans — on extending the reductions for all.
"There's a middle ground. Let the tax cuts expire for those earning over $500,000," Kaine tells the camera, calling it "the fiscally responsible thing to do."
In an Indiana ad, Senate Democratic hopeful Rep. Joe Donnelly attacks his GOP rival, tea party favorite Richard Mourdock, using presidential debate footage of Romney saying he got little done as Massachusetts governor "by saying it's my way or the highway." Mourdock "is all about my way or the highway," the ad says.
And in a Wisconsin Senate debate last week, GOP candidate Tommy Thompson distanced himself from the House-passed budget written by Rep. Paul Ryan, the Republican vice presidential candidate. His rival, Democratic Rep. Tammy Baldwin, repeatedly linked him to the blueprint that she argued would raise taxes on the middle class.
"You're absolutely wrong," Thompson told Baldwin. "I have a plan completely different from Paul Ryan."
Meanwhile, spending has continued to accelerate on congressional races by both political parties and outside groups, including Crossroads GPS backed by former White House GOP strategist Karl Rove and unions such as the SEIU.
According to the nonpartisan Sunlight Foundation, which monitors campaign spending, outside groups have spent $161 million since June 1 on House races and $156 million on Senate races, with Republicans benefiting from a modest advantage.
But that spending has accelerated in recent days, especially on the GOP side, the foundation found.
In the week ending last Friday, groups have spent $13 million to help House Democratic candidates and $22 million for House Republicans. Senate Democratic hopefuls have benefited from $6 million, Senate Republicans from $10 million.
In one instance, an obscure conservative group, the Government Integrity Fund Action Network, spent $1.1 million for an ad attacking Democrat Elizabeth Esty, who is seeking an open House seat in Connecticut. That is a huge expenditure for a House race.
The Senate Democratic campaign committee spent $1.6 million to advertise against Allen in Virginia.
Eds: AP reporter Donna Cassata contributed to this story from Wausau, Wis., and Julie Carr Smyth contributed from Columbus, Ohio.
- Photo gallery: Christmas around the world
- Heroes 2014: Ex-CIA officer uses...
- Officer kills armed 18-year-old near Ferguson
- Our six heroes of 2014
- On Christmas, Obama marks end of Afghan combat
- NORAD 'tracks' Santa's journey across globe
- Capacity crowds pack screenings of 'The...
- Ex-President George H.W. Bush to stay...
- NYPD: Cop ambush killer told passers-by... 15
- Going it alone, Obama rocked the boat... 14
- Officer kills armed 18-year-old near... 11
- Pope in blistering critique of Vatican... 9
- Key developments in the case of slain... 9
- Obama 's Christmas in Hawaii: Carols,... 9
- Killings of 2 New York officers trigger... 6
- Senate, CIA agree torture program was... 6