The Democratic Congressional Campaign Committee (DCCC), the House Democrats' campaign arm, declared victory in Tuesday’s special election in Pennsylvania, even as experts declared the race too close to call.

“I want to congratulate Conor Lamb and his team of grassroots supporters on an incredible victory. I’m excited to have Conor as a colleague and look forward to working with him on the critical issues facing our country,” DCCC chairman Rep. Ben Ray Luján (D-N.M.) said in a statement.

Democrat Conor Lamb held an 847-vote lead over Republican Rick Saccone with nearly all votes counted late Tuesday night in the special election for Pennsylvania's 18th Congressional District. More absentee votes from GOP-leaning areas have not yet been counted, but it’s unclear whether those absentees will cut the gap.

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The Associated Press deemed the race too close to call shortly before 11:30 p.m.

The National Republican Campaign Committee (NRCC) pushed back on the DCCC victory claims, saying they expect Saccone to pull through once all the votes are counted.

“This race is too close to call and we’re ready to ensure that every legal vote is counted. Once they are, we’re confident Rick Saccone will be the newest Republican member of Congress,” NRCC communications director Matt Gorman said in a statement.

Republicans are hoping to stave off a Democratic upset in the western Pennsylvania district that President Trump Donald John TrumpBiden leads Trump by 36 points nationally among Latinos: poll Trump dismisses climate change role in fires, says Newsom needs to manage forest better Jimmy Kimmel hits Trump for rallies while hosting Emmy Awards MORE won by nearly 20 points in the 2016 election.

The special election was necessitated after longtime Rep. Tim Murphy Tim MurphyBiden receives endorsements from three swing-district Democrats A federal abortion law might be needed Female Dems see double standard in Klobuchar accusations MORE (R), who is strongly anti-abortion, resigned in October amid allegations he asked a woman he was having an affair with to get an abortion.

Luján on Tuesday touted the race as an indicator that Democrats will compete with Republicans in midterm races across the country.

“These results should terrify Republicans,” he said.

“There are more than one hundred districts more favorable for Democrats than this one and we look forward to competing hard in every single one,” he added.