Rep. Charlie Dent (R-Pa.) has fended off challengers before in this moderate district, but national Democrats this year finally got the candidate they've always wanted, Bethlehem Mayor John Callahan. While most stories these days focus on the number of seats the GOP will win back in 2010, the National Republican Congressional Committee is also focused on holding on to seats like Dent's.

That's why the committee has begun airing a radio ad in the Allentown-based 15th District that knocks Callahan for raising taxes. The 60-second ad, which you can listen to here, follows the rhyming scheme of "Twas the Night Before Christmas."

Here's a sampling:

'Twas two nights before Christmas, when in Bethlehem/ John Callahan was voting, again and again/ An increase he supported on property tax/ A five point five percent increase he surely did pass

"John Callahan's record of raising taxes four times in four years shows that he has abandoned fiscal discipline and adopted big-government policies that create bureaucracy, not jobs," NRCC spokesman Ken Spain said in announcing the ad. "After voting time and time again to pile on burdensome tax increases, it is clear that middle-class families of Pennsylvania cannot afford John Callahan's reckless job-killing agenda."

Dent has won the 15th District with 59%, 54% and 59% of the vote since coming to Congress in 2004. President Obama won it with 56% last year, and John Kerry edged out George W. Bush in 2004 by just more than 700 votes. The district has voted for the winning gubernatorial candidate in the last six elections, according to the Almanac of American Politics.

The Democratic Congressional Campaign Committee is set to launch a radio ad of its own in the district, as it targets five Republicans who voted against the Wall Street reform bill Friday.

"Congressman Dent voted to let Wall Street continue the same risky practices that crippled retirement accounts and left taxpayers on the hook for $700 billion dollars," the 60-second ad will say.