The first day of July brought a trio of developments in the New York’s 2010 special election for the U.S. Senate seat held by Democratic appointee Kirsten Gillibrand .

Nine-term Republican Rep. Peter T. King gave his strongest public signal yet that he will not enter the Senate race, citing the huge amounts of campaign money he would need to raise and his desire to focus on a high-profile new assignment that his House seniority has recently brought him. A Senate race opt-out by King, the most prominent Republican who has been publicly mulling the race, could leave the GOP scrambling for a challenger in a state where recent setbacks have left the party with a very short list of strong statewide candidate prospects.

But that hardly means Gillibrand is out of the woods, as she seeks election to fill out the final two years of the term Democrat Hillary Rodham Clinton vacated in January following her confirmation as secretary of State in the Obama administration. Gillibrand’s potential vulnerability was underscored Wednesday by a local news report that Democratic Rep. Carolyn B. Maloney definitely will launch a strong challenge to the incumbent in the September 2010 Senate primary.

And a new independent poll showed Maloney in a virtual tie with Gillibrand, who still is little known to many New Yorkers after more than five months in the seat.

The word that Maloney has firmly decided to take on Gillibrand was first reported Wednesday by the New York Daily News and the Associated Press and was confirmed by CQ Politics. “Congresswoman Maloney has made her decision,” said a statement issued by the Democratic consulting firm of Trippi & Associates. The release also set a time frame for her campaign roll-out, stating, “Congresswoman Maloney is putting together a campaign team and will make her announcement in two weeks.”

Maloney — a nine-term House incumbent who represents a New York City district that takes in parts of Manhattan and Queens — was among a number of party dissenters after Democratic Gov. David A. Paterson made his surprise choice of then-Rep. Gillibrand to succeed Clinton. Although Gillibrand had earned a “rising star” label with her 2006 victory over Republican Rep. John E. Sweeney in an upstate district that had long been a GOP stronghold, she had just begun a second House term when she was elevated to the Senate, and Maloney and others protested that Paterson should have picked a more experienced legislator.

Maloney also was among those who portrayed Gillibrand’s House voting record as too conservative for the strongly liberal-leaning New York Democratic base, highlighting her breaks with the party line on issues such as immigration and gun control.

Gillibrand nonetheless appeared through the spring to be solidifying her position for next year’s primary, working to secure endorsements from Democratic politicians and liberal support groups. She got a boost in May when Democratic Rep. Steve Israel of the Long Island-based 2nd District withdrew a primary threat at the behest of President Obama, and another in June when 4th District Rep. Carolyn McCarthy of Long Island, an outspoken advocate of gun control, also said she would not enter the primary.

But Maloney has said throughout that she will not yield to Gillibrand. And the poll conducted June 23-25 released Wednesday by the unit at New York’s Marist College showed the two in a virtual dead heat, with 37 percent of the registered Democratic respondents preferring Gillibrand, 38 percent supporting Maloney and 25 percent undecided.

Gillibrand’s hopes hinge on more voters getting to know her better and liking what they learn. The poll showed 24 percent of the respondents rated her job performance as “excellent” or “good,” with 30 percent saying “fair” and 13 percent saying “poor.” But the most glaring number is the 33 percent who declared themselves “unsure.” Gillibrand, though, is making some progress on gaining visibility among voters, as that 33 percent figure is down from 43 percent in the organization’s previous poll in May.

And the poll gave the state’s struggling Republicans little reason to rejoice. The pollsters set up a hypothetical matchup between Gillibrand and Republican former Gov. George E. Pataki, and the Democratic incumbent edged ahead by 46 percent to 42 percent. Gillibrand in May had trailed by 38 percent to 46 percent for Pataki, who has been courted by a number of Republicans to run but has given no public indication that he plans to do so.

Gillibrand held a much bigger lead of 48 percent to 32 percent over GOP House veteran King.

But that news came after King was already quoted in the Long Island newspaper Newsday as saying the chances he will run against Gillibrand in 2010 are “less than 50-50.” He told the publication he has informed House Minority Leader John Boehner of Ohio that he probably will not be running for Senate, citing his desires to focus on his duties as a recently appointed member of the House Select Committee on Intelligence, but also noting the fundraising demands of a Senate race that he would be seriously challenged to meet.