Updated: 4:22 p.m.

The Democratic Congressional Campaign Committee is dropping a $500,000 TV ad buy in New York — a sign of growing worry among party insiders that they could lose next week’s special election to replace ex-Rep. Anthony Weiner (D).

A Republican source confirmed the DCCC buy, first reported by National Journal, to Roll Call. The buy was reported within hours of the news that the Democratic group House Majority PAC is also going up on TV to try to boost state Assemblyman David Weprin’s (D) campaign against Republican Bob Turner.

The DCCC ad hits Turner for saying at a recent debate that he “never met a loophole I didn’t like.” A male narrator intones, “Corporate executive Bob Turner lives the high life” as an animation of a small jet swooshes by on the screen. As with the TV spot Weprin launched on Wednesday, the DCCC highlights the New York Times’ endorsement of the Democrat.

Turner’s campaign spokesman responded that the buy was an indication that “President Obama and [Minority Leader] Nancy Pelosi are in full panic mode in NY-9.”

“This district is greater than 3-1 Democrat, yet the race is tied,” William O’Reilly said in a statement.

The House Majority PAC’s six-figure ad buy will begin airing Friday in the New York market on cable and broadcast. A source familiar with the ad said it focuses on what they say is Turner’s connection to the tea party.

Recent polling has shown the 9th district race between Weprin and Republican Bob Turner to be unexpectedly close. Roll Call rates the race as Leans Democratic because it remains more likely than not that Weprin will eke out a meager victory in the traditionally Democratic district. But Democrats in the Big Apple now believe momentum has swung behind Turner. And, in an election where both campaigns predict 20 percent turnout, an upset is certainly possible.

Republican leaders on Capitol Hill have sent Turner late money in an effort to help him capitalize on his perceived momentum.

A nonpartisan poll of the race conducted by Siena College is to be released Friday morning.

The diverse political contours of the district, the more than 3-to-1 Democratic voter registration advantage, and the strong organized labor infrastructure initially pointed to an easy win for Weprin, an orthodox Jew from a storied political family.

But a simmering undercurrent of dissatisfaction in the district with the president has roiled the race. And Weprin, who has encountered some difficulty as a candidate for federal office, finds himself struggling to seal the deal with voters.

Early one morning two weeks before the election, Roll Call asked Weprin whether he thought he would win.

“I do. I do,” he said confidently.

Asked by how much, he declined to speculate but then said, “I hope it’s more than one vote, but I think, you know, I expect to win on Sept.13.”