(CNN) - With one week to go until election day, a once little-talked-about contest to fill a vacant congressional seat in upstate New York is now more than ever firmly in the national political spotlight.
And the race between Republican state Assemblywoman Jane Corwin, Democrat Kathleen Hochul, the Erie County clerk, and Jack Davis, a once-conservative Democrat who is running as a so-called tea party candidate, is becoming more and more a referendum on House Republican plans to alter Medicare, as both sides filling the airwaves with television ads attacking the other side over Medicare.
The winner of the May 24 special election will fill the seat of Republican Rep. Chris Lee, who quickly resigned in April hours after the gossip website Gawker posted photos and e-mails from the married congressman soliciting a date with a woman through the website Craigslist.
House Majority PAC, an independent Democratic leaning group, went up with a new ad Tuesday that claims that "Corwin's plan would essentially end Medicare" and that seniors would "sacrifice." The group says the ad will run for the week leading up to election day in Buffalo and Rochester, the two major media markets in New York's 26th congressional district.
The House Majority PAC ad comes one day after Corwin's campaign went up with a commercial attacking Hochul on Medicare.
"Kathy Hochul: A false campaign about Jane Corwin's position on Medicare when the truth is it's Hochul who says she would cut Medicare and Social Security."
Hochul's campaign, the Democratic Congressional Campaign Committee, the National Republican Congressional Committee, and American Crossroads, an independent group that leans Republican, have also gone up with commercials in the district.
This should be a safe seat for the GOP. In 2008, Republican presidential nominee John McCain won the district by six points and Lee won re-election by a three to one margin last November. But recent polls suggest the contest is competitive between Corwin and Hochul. Two of the top non-partisan political handicappers, the Cook Political Report and the Rothenberg Political Report, Monday changed their ratings of the race: Cook to "toss up" and Rothenberg to "toss up/lean Democrat."
Top House Democrats say the close race is evidence that House Republicans' support for a proposal to dramatically change Medicare is already hurting GOP candidates with voters. Asked about the impact of the Medicare issue on the New York race, House Democratic Leader Nancy Pelosi of California said last week the contest "certainly is a race that was not in play and now it is."
Massachusetts Democratic Rep. Ed Markey was more blunt, predicting the issue is producing blowback for Republicans not just in New York.
"Medicare has razor-blade-sharp edges and it's drawing political blood in New York, as it's going to across this country," Markey said.
The House Republican 2012 budget, authored by House Budget Committee Chairman Rep. Paul Ryan of Wisconsin, passed the House last month without a single Democratic vote and included a proposal to overhaul Medicare. Under the plan, the government would no longer directly pay medical costs for those 55 and younger, but instead would offer subsidies for seniors to use to get private health insurance coverage. A recent CNN/Opinion Research Corporation poll indicated that 49 percent of Americans prefer President Obama's approach on Medicare, with four in ten favoring the GOP proposals on Medicare.
But some Republicans disagree that the race is close because of Medicare.
Paul Lindsay, spokesman for the House Republicans' campaign arm, said the race is close because of the impact of Davis, the third-party candidate.
"This race is close because Republican Jane Corwin is running against two Democrats, one of whom is deceiving voters by claiming to be a Tea Party candidate," Lindsay said.
There's a similar message from FreedomWorks. The independent conservative grassroots group, which has organized many of the larger tea party movement events over the past two years, launched a campaign to expose "Jack Davis's record as a big government liberal."
And the Tea Party Express, one of the most well known and politically active of the national tea party groups, is also mounting a campaign in the district to denounce Davis "for deceptively giving himself the 'tea party' title when he does not truly support core tea party values of the movement."
Local tea party groups also weighed in Tuesday, holding two events in support of Corwin.
Here's another sign of how important this contest is to the GOP: House Speaker John Boehner of Ohio and House Majority Leader Eric Cantor of Virginia also made trips to the district to campaign for Corwin in recent days. And Sen. Charles Schumer of New York went to the district last weekend to campaign for Hochul.