Panic is starting to set in among Democrats who were expecting an easy win in the Sept. 13 special election for Anthony Weiner's old congressional seat.

All the ingredients for an upset in the race between Democrat David Weprin and Republican Bob Turner for an overwhelmingly Democratic New York City district are coming into place: a Democrat who's made a series of mistakes, a Republican who's tapped into unrest over President Barack Obama's policies and unease over the local machine politics at play. And though the race still seems like the Democrats' to lose, exasperation is building from the amount of energy and money being sapped by what should have been a no-effort race by almost any measure.

"It's frustrating and annoying that a race that should be a slam-dunk has become so competitive that resources are being used that should be going to other congressional races," said Scott Levenson, a New York City-based Democratic consultant. "It's still a winnable race. But given the effort to date, no one is going to bet on it."

"'Nervous' is the word I would use," said Evan Thies, a Democratic consultant in Brooklyn. "Unless something suddenly shifts significantly, this is a crapshoot. I don't think either side knows what is going to happen."

Turner's traction is creating an embarrassing prospect for Democrats: Losing a seat on prime Democratic turf that until just a few months ago was held by an outspoken liberal regarded as a rising star and potential future New York City mayor.

The latest log on the fire: an internal poll released by Turner's campaign Thursday showing a tie at 42 percent each, which followed a Siena Research Institute poll released last month that showed Weprin leading Turner by a surprisingly narrow 48 percent to 42 percent.

Weprin spokeswoman Elizabeth Kerr pushed back hard on the new poll Thursday evening, citing the Democrat's endorsement by The New York Times this week and cash lead as evidence that her candidate's still coasting.

"Sham polls and hyped-up coverage can make a race look more competitive than it really is, but when you look at the action on the ground, it's clear that voters will reject Bob Turner's radical plan to end Medicare and raise taxes on the middle class," Kerr said.

But Weprin's campaign has been in overdrive the past week, flooding reporters' inboxes with a seemingly endless series of press releases hawking endorsements from Democratic figures and labor groups. And in a signal of how intense and far-reaching the Democratic fear has gotten, the president's political operation got involved Thursday.

Jeremy Bird, Obama for America's national field director, sent out an email to supporters inviting them to phone bank for Weprin. "The calls you make could be the ones that put him over the top," Bird wrote.

Weprin - a state assemblyman given the nomination by the Queens Democratic Party after Weiner resigned from the seat in June - has made a series of recent missteps that have jeopardized his candidacy. This week alone, Weprin told the New York Daily News that the national debt is $4 trillion, rather than $14 trillion, and unexpectedly bowed out of a scheduled debate, blaming the already passed Hurricane Irene - errors that have earned days of ribbing in the New York City tabloids.

Weprin has also had trouble navigating his connection to Obama, who's facing his own dipping numbers in the district. At a press conference last month, Weprin declined to answer whether he planned to vote for Obama. The next day, he released a statement clarifying that he would, in fact, support the president. Then, in an interview this week with the Jewish Press, Weprin hedged, saying, "I will probably not refuse to endorse him because I think I will be more effective by supporting him but at the same time, being very strongly against him on some of his policies."

That's provided an opening for Turner, who's waged a vigorous effort to tie Weprin to Obama. The Republican has gone so far as to air TV ads slamming Obama and Weprin for their support of the construction of the so-called ground zero mosque, which show a picture of the president next to an image of the burning World Trade Center and a follow-up mailer expanding on the argument.

To some extent, Weprin has also been hobbled by his image as the product of the Queens Democratic machine that nominated him. While Turner has painted himself as an independent-minded businessman, he's portrayed his Democratic foe as a puppet of party higher-ups - all with an eye toward tapping into voters' lingering anger at incumbents.

For all the Democratic nervousness, the district has long favored Democrats - most recently in November, when Weiner beat Turner convincingly. While Turner has scored a few points, Democrats monitoring the race say, numbers still strongly favor a Democrat.

That said, there's concern that even a close race would establish a negative story line for Democrats heading into 2012. After a string of upset wins in upstate New York special elections over the past few years, a narrow Democratic win in a liberal-oriented district would be read as a sign of the party's dimming fortunes.

"In a district that has an overwhelming Democratic registration, with polls this close, it's frustrating and concerning," said Michael Tobman, a New York City-based Democratic consultant and former aide to Sen. Chuck Schumer. "It's concerning because it speaks to larger trends, and you have to be aware that special elections are often bellwethers."