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ABC News’ Joel Siegel ( @joelmsiegel ) reports:

There is grim news today for the White House and the Democratic Party in the special election to fill Anthony Weiner’s vacated congressional seat in New York.

Although Democrats hold a  three to one registration advantage over Republicans in the district, Republican Bob Turner has opened a lead, grabbing 50 percent, compared with  44 percent for Democrat David Weprin, among likely voters, according to a new Siena Research Institute poll.

Weprin stood at 48 percent and Turner 42 percent  in a Siena poll taken one month ago.

The election is next Tuesday.

A Turner victory would be an ominous sign for Democrats and President Obama’s re-election campaign, as the district, which  spans  Brooklyn and Queens, is filled with the kind of white, middle-class, usually reliable Democratic voters that the president  needs in his corner to get re-elected.

But the poll found voters in the district are down on the president, and the direction of the country.

Forty-three percent have a favorable opinion of Obama, while 54 percent have an unfavorable opinion, according to the poll.  Nineteen percent believe the U.S. is on the  right track, ” while 74 percent say the country is on the wrong track. Both sets of numbers are largely unchanged from a month ago.

What has changed is the voters’ views of the candidates: Weprin’s unfavorable ratings shot up, to 41 percent, from 24 percent a month ago. And by a 43-32 percent margin, likely voters say Turner is running the more positive campaign

“It’s a perfect storm for Turner and the Republicans,” said Steven Greenberg, a spokesman for the Siena Research Institute.

Sensing the seat could be slipping away, the national Democratic Party has begun pouring money into the race – including a $500,000 infusion this week from the Democratic Congressional Campaign Committee. Even if Weprin can pull out a victory, it is still an enormous expenditure in an election Democrats once believed was a lock.

With the possibility of a monumental upset now within reach, the Republican National Committee answered with an email appeal this afternoon seeking donations, saying the money was needed because “the Obama Democrats just put $500,000 into the race to defeat Bob Turner and keep this seat in their liberal hands.”

“We have a strong conservative candidate in Bob Turner who has the opportunity to win a congressional seat in the heart of New York City,” party Chairman Reince Priebus wrote in the email. “He is facing a career politician who will vote in lockstep with Nancy Pelosi in support of Barack Obama’s failed economic policies.”

Weprin has fallen behind, despite his longstanding political ties in the district. He’s a state assemblyman and the son of a former state assembly speaker.

Turner has never held elected office before, although he ran a surprisingly close race in 2010 against Weiner, who later gave up the seat in a scandal over lewd photos of himself he’d Twittered. Turner, 70, is a retired television executive whose claim to fame – or, perhaps, infamy – - is that he helped to create Jerry Springer’s bawdy television show in the 1990s.

Although Turner has opened a lead, Greenberg cautioned that the race would go down to the wire.

“While Turner leads and has momentum on his side, this is still a heavily Democratic district and in a low turnout special election, the campaigns’ get-out-the-vote operations are going to be key. There’s still a lot of campaigning yet to happen,” Greenberg said.

“Will the late infusion of national money and advertising change voters’ minds or move voters who hadn’t been planning on voting to come out and cast a ballot? These are all questions that will not be answered until Tuesday at 9 p.m..”

The Siena poll has a margin of error of plus or minus 3.3 percentage points.