David Malpass will formally launch his campaign against Sen. Kirsten Gillibrand on Monday, filing paperwork with the Federal Elections Commission, City Hall has learned.

Malpass will establish a full committee, not just an exploratory committee, putting him up against former Nassau County legislator Bruce Blakeman for the Republican nomination.

A former deputy assistant treasury secretary for President Ronald Reagan and deputy assistant secretary of state for President George H. W. Bush, Malpass is the founder and president of the research and consulting firm Encima Global and writes the “Current Events” column for Forbes. Before that, he was chief economist for Bear Stearns.

Malpass spent most of last week in the capital meeting with the National Republican Senatorial Committee and the Club for Growth. He has already started putting together a campaign team, hiring Nicholas Lence O’Reilly Strategies and Jamestown Associates, a New Jersey-based firm which worked most recently with on the gubernatorial campaign of Chris Christie.

Though Malpass has been meeting with Republican and Conservative county chairs over the past few weeks, his candidacy has so far remained below the radar to most New Yorkers and has not even been an option in polls. Those polls, though, show Gillibrand far ahead of Blakeman—and according to the late February Siena poll, picking up points against former Gov. George Pataki, who has not entered the race.

Malpass’ entrance comes a week after two more potential Gillibrand challengers dropped out of the running, with both former Tennessee Rep. Harold Ford and Daily News publisher Mort Zuckerman ending their explorations of candidacies. As of now, only Jonathan Tasini is left as a primary challenger for Gillibrand on the Democratic side.