Michigan's 1st district, which is held by retiring Rep. Bart Stupak (D), is seeing an influx of spending by national Republicans and their allies. 

The National Republican Congressional Committee has reserved some $700,000 in airtime in support of its nominee, Dan Benishek.

Meanwhile, the American Future Fund has dropped $273,000 on ads airing Sept. 15 to Oct. 12, according to a Republican strategist tracking ad buys in the race. And the group Americans for Prosperity spent $93,000 on ads that aired in August.

The Democrat running against Benishek, state Rep. Gary McDowell, is slated to get a total of $711,000 in ad spending help from the Democratic Congressional Campaign Committee.

McDowell has already dropped $200,000 of his own campaign money on TV ads, according to the GOP strategist.

But traditional Democratic allies such as unions have not made an investment in the 1st district, even as they air ads in other competitive Michigan races.

On Tuesday, Benishek used one of his first TV ads of the campaign to rebut Democrats' claims he wants to "privatize Social Security."

"You can tell it's almost Election Day: they're starting with the scare tactics," Benishek says in one of two spots released Tuesday. "The truth is I'm fighting to protect Social Security."

He spent $85,000 on airtime for the ads, the strategist said.

Benishek was recently hit with a TV ad from the DCCC that said he "supports a plan that would let Wall Street gamble with your Social Security."

The DCCC's spots haven't proved effective. Two recent polls have shown McDowell trailing Benishek from 3 to 16 points.