Riding what they say is strong opposition to a Republican plan to change Medicare, Democrats won back a seat in the U.S. House on Tuesday, taking a historically GOP district  just seven months after being blown out in that same race in last November's elections.

The victory went to Democrat Kathy Hochul, who will take the seat once occupied by ex-Rep. Chris Lee (R-NY), who resigned after his shirtless photos showed up on Craigslist, where he was trolling for dates with women who weren't his wife.

The Republican in the race, Jane Corwin, was battered by Democratic attacks after she embraced a House Republican budget plan that included major reforms in Medicare.

Hochul ran up big margins in the suburbs of Buffalo, winning easily in Erie and Niagara counties, more than offsetting Republican votes in rural areas of the district that went to Corwin.

Last November, Republicans won this seat with over 68% of the vote; on Tuesday night, Corwin could barely muster 43%.

A swing of 25 points in seven months is not something to gloss over.  It's also a district that John McCain won 52-46% over Barack Obama in 2008.  In other words, it's been reliably Republican in recent years.

After the loss, Republicans bitterly complained that Democrats distorted the details of their budget plan, especially the Medicare details, all in an effort to do well at the ballot box.

Democrats say this is just the start of their broadsides focused on GOP Medicare changes, which suddenly have Republicans playing defense, just seven months after their big midterm election wins.

"We served notice to the Republicans that we will fight them anywhere in America when it comes to defending and strengthening Medicare," said Rep. Steve Israel (D-NY), who heads the Democratic National Campaign Committee.

"The American people will continue to hold House Republicans accountable for their plan to end Medicare from now until election day 2012," Israel added.

Republicans meanwhile tried to downplay the loss, pointing out that the Tea Party candidate made the difference in the race, and that this one contest is not an indicator of more troubles down the road for the GOP.

Time will tell on that obviously, but I do sort of wonder whether Republicans have already seen their high water mark, much as Democrats started to lose momentum two years ago around this time after they pushed through a cap-and-trade bill in the House, and started muscling a health reform bill through key committees in the chamber.

For now, there's no need for the GOP to panic, as they still control the House by a 239-193 margin.

It was just one seat, after all.

Or was it?

I'll let the two parties spin you on that question.