The upstate New York House race between Rep. Bill Owens (D) and his Republican challenger, Matt Doheny, is in a statistical dead heat, and may hinge on how many voters know that third-party candidate Doug Hoffman has suspended his campaign.

According to a poll released Thursday by the Siena College Research Institute, the outcome of the race in the 23rd district could be determined by how many voters cast their ballot for Hoffman, whose name remains on the ballot under the Conservative Party line.

The survey found that when respondents were told Hoffman had suspended his campaign, Owens and Doheny were tied at 42 percent, with Hoffman getting 4 percent. When they were not told about Hoffman’s decision, Owens led Doheny, 40 percent to 37 percent, with Hoffman receiving 15 percent of the vote. The poll of 623 likely voters was conducted from Saturday through Tuesday and has a 3.9-point margin of error.

“Will voters know or won’t they know that Hoffman has suspended his campaign? That question will determine how many votes are siphoned away on the Conservative Party line for the two major party candidates,” Siena poll director Steven Greenberg said.

The survey found that Doheny had improved his standing from earlier this month, when Owens led by 5 points. Owens has the support of almost three-quarters of Democrats but trails Doheny among independents by 6 points. When voters don’t know that Hoffman has suspended his campaign, Doheny receives only 52 percent of GOP support. When they are informed about the decision, Doheny’s Republican support rises to 60 percent.

“Clearly, informing voters — particularly Republicans — that Hoffman is out is crucial to the success or failure of Doheny’s campaign heading into the closing days,” Greenberg said. The National Republican Congressional Committee has recently launched an advertising campaign in the district to boost Doheny.

Owens defeated Hoffman in a special election last year after Republican candidate Dede Scozzafava dropped out of the race.