(CNN) - Peter King made it official Monday.
The Republican congressman from New York State announced that he won't take on Democrat Kirsten Gillibrand next year when the appointed senator runs for the final two years of Hillary Clinton's term.
After Clinton announced that she would step down from her seat to become secretary of state, King - the last remanning GOP congressman from Long Island, a former Republican bastion - hinted that he might make a bid for statewide office. But in recent months, most political observers wrote off any actual run by King.
King says it came down to money.
"The reality is that a statewide Democratic candidate starts the race with a voter registration edge of almost 3 million. To overcome such a large margin, there would have to be intensive media coverage of the race and I would need to raise at least $30 million," said King in a statement.
He added that he would have made a bid for the Senate if New York Governor David Paterson had named Caroline Kennedy to Clinton's seat rather than Gillibrand.
"Her candidacy would have generated the media coverage and financial contributions necessary for me to run a competitive race," said King.
"That race was not to be. Senator Gillibrand generates neither strong support nor opposition. This makes it virtually impossible for me to raise the campaign funds I would need to overcome the built-in Democratic registration advantage and the countless millions of dollars which the Democrats will make available to Senator Gillibrand."
King is one of just three New York Republicans in Congress, one of whom - upstate Rep. John McHugh - plans to step down to serve as secretary of the army in the Obama administration.
–CNN Congressional producer Deirdre Walsh contributed to this report