Democrat Kathy Hochul has a narrow lead heading into the final stretch of the special election in western New York, according to a Siena Research Institute poll released Saturday.

Hochul led Republican Jane Corwin 42 percent to 38 percent in the survey of 639 likely voters taken May 18-20. The poll had a 3.9 point margin of error.

Third party candidate Jack Davis drew 12 percent, a dramatic drop in support from an earlier Siena poll. Davis is running on the Tea Party ballot line in Tuesday’s election and the new poll seems to confirm GOP fears that he will act as a spoiler who will allow Democrats to capture a solidly Republican district.

The new numbers represent a big shift from an earlier Siena poll released in late April that showed Corwin ahead of Hochul by a 36 percent to 31 percent margin.

Hochul’s lead now is attributed to the support she’s picked up from Independents, who have peeled away from Davis as national Republicans and their allied outside groups have targeted him in TV ads and portrayed him as a spoiler with Democratic roots.

“While Corwin picked up support among Republicans and held or picked up a couple of points among Independents and in every region of the district, Hochul gained fourteen points with Democrats and eighteen points among Independents,” Siena College pollster Don Levy said in a news release.

Democrats have increasingly sought to portray the race as a referendum on Rep. Paul Ryan’s (R-Wis.) budget proposal and the debate over his plan to revamp Medicare. The Siena poll showed 21 percent of respondents said Medicare was the most important issue for them in the special election. Of those, 74 percent said they are backing Hochul.

Corwin’s favorability rating has slipped considerably since last month’s Siena poll. The new survey showed her with a 43 percent/49 percent favorable/unfavorable rating while 55 percent of respondents said they viewed Hochul favorably. The advertising barrage has significantly driven up Davis’ negatives. The wealthy businessman who has run previously in the district as a Democrat is now viewed unfavorably by 64 percent of respondents.

The Democratic Congressional Campaign Committee immediately trumpeted the survey results, sending out an email noting Republican Carl Paladino carried the 26th district with 61 percent in the 2010 gubernatorial race. Paladino was crushed statewide by now-Gov. Andrew Cuomo (D). Cuomo stars in a new web ad for Hochul.

The National Republican Congressional Committee and allied outside groups, namely American Crossroads and the U.S. Chamber of Commerce, have spent more than $3.3 million to compete in the district. Democrats and their outside groups have invested roughly $1.86 million in the special election.

Corwin has poured $2.76 million of her own money into the race, including $300,000 she reported loaning her campaign this week. Davis has been solely self-funding his campaign, spending more than $2.6 million in personal funds to this point.

Both parties are now focused on the ground game and making sure voters get to the polls on Tuesday. Sen. Kirsten Gillibrand (D-N.Y.) is campaigning Saturday with Hochul at a union hall in the district.

Even if Democrats do win the special election, the district is likely to be eliminated when state legislators redraw Congressional lines later this cycle.