The two major-party candidates were Scott Murphy, a Democrat and private businessman, and Jim Tedisco, a Republican and the minority leader of the New York State Assembly.

The 20th congressional district has historically been conservative, and early polls favored Tedisco, but by February 2009 the race was considered a toss-up.

The Republican Party considered the election to be a referendum on President Obama's economic policy and as such, injected significant funding into Tedisco's campaign, using well-known Republicans such as former Speaker of the House Newt Gingrich, Congressional Minority Leader John Boehner, and former New York governor George Pataki for support.

Major issues brought up during the campaign were the candidates' positions on President Obama's stimulus plan, which Tedisco did not take a stance on until late in the race.

New York's 20th congressional district in 2009 encompassed all or part of Columbia, Dutchess, Delaware, Essex, Greene, Otsego, Rensselaer, Saratoga, Warren, and Washington counties.

[1] Traditionally conservative, it had been considered a safe seat for Republicans[Note 1] until Blue Dog Democrat Kirsten Gillibrand defeated incumbent John E. Sweeney in the 2006 election.

[8] The district's seat became vacant in January 2009 when Governor David Paterson appointed Gillibrand to the United States Senate to replace Clinton.

[14] Richard Wager, a former aide to New York City Mayor Michael Bloomberg, and State Senator Stephen Saland had also been mentioned.

[38] The vast majority of the rejected signatures were from voters who put down their mailing address instead of the municipality in which they physically lived.

[41][42] The second debate, sponsored by WMHT and the Times Union, took place on March 19 between Murphy and Libertarian candidate Eric Sundwall.

[40][43][44] Jim Tedisco held a town hall meeting rather than attend, claiming the debate was not one of the four originally agreed upon.

That same day, Democratic National Committee (DNC) Chairman Tim Kaine emailed 500 of the party's top donors asking them to contribute to Murphy's campaign.

[58] The New York State United Teachers made an effort to call its members on Murphy's behalf, while the National Right to Life, National Republican Trust and New York State Rifle and Pistol Association organizations paid for ads and mailings supporting Tedisco.

[63] Murphy spent the first months of the campaign criticizing Tedisco's early refusal to disclose his position on President Obama's American Recovery and Reinvestment Act.

[65] By mid-March, a provision in the stimulus package that grandfathered in bonuses paid to executives at troubled insurance giant AIG and other TARP recipients became a campaign issue.

[84][85] Columbia County's Board of Elections amended its tally the following day, reducing Murphy's lead to 25 votes.

He resigned the position of Assembly Minority Leader on April 5 in preparation for a transition to Congress,[88] and was replaced by Brian Kolb the following day.

[112] In an editorial, the Wall Street Journal contended that being an "Albany careerist" and running confusing campaign ads had hurt Tedisco.

[113] Tedisco's loss immediately made him appear vulnerable to Democrats hoping to capture his seat in the Assembly.

Scholz had worked on Murphy's campaign and had received praise from Larry Bulman, the chairman of the Saratoga County Democratic Committee.

[118][119] Murphy served the remainder of his term, but lost a reelection bid on November 2, 2010, to challenger Chris Gibson, a retired Army colonel.