Posted by Scott M. Stringer, the Manhattan borough president, has created a federal committee to explore challenging Kirsten E. Gillibrand, the newly appointed United States senator, in the Democratic primary next year.
Mr. Stringer filed papers with the Internal Revenue Service on to create the exploratory committee on Monday, according to an aide. The move means that Mr. Stringer is free to raise and spend money on polls, travel and staff but cannot declare himself a candidate.
Mr. Stringer, who has been talking to political consultants in recent weeks as he seeks to assemble a campaign team, is among a growing group of potential challengers considering a run against Ms. Gillibrand, who was appointed to the Senate in January by Gov. David A. Paterson.
