Congressman Steve IsraelSteven (Steve) J. IsraelIn dueling memos, we are seeing President Trump in panic mode Trump's State of the Union: Don't pass up this chance for repentance The happiest place on earth is now the center of American polarization MORE (N.Y.) is planning to announce soon that he is challenging Sen. Kirsten GillibrandKirsten Elizabeth GillibrandBritish health secretary fires back at Trump over universal health care claims Trump on Dems’ ‘universal' health-care push: ‘No thanks’ Gillibrand calls for DOJ to investigate US Olympic Committee over abuse scandal MORE (N.Y.) in next year's Democratic Senate primary, the New York Post's Fred Dicker reports.

Israel has been rumored to be considering a run. He hired Lisa Gioia, a high profile New York fundraiser who works for the Ensler Group, last month. And while he hauled in an unimpressive $282,000 in the first quarter, he is sitting on $1.7 million in his campaign warchest as of the end of March.

A call into Israel's congressional office was not immediately returned.

Gillibrand, however, significantly outraised Israel in the first quarter, hauling in $2.3 million. She currently has $2.2 million in her campaign account. Despite that large warchest, recent polling has shown Gillibrand may be vulnerable.

Israel, who was first elected to his Long Island district in 2000, is one of several potential Gillibrand challengers. Rep. Carolyn Maloney (D) has said she is considering the race, as has Rep. Carolyn McCarthy (D).

Interestingly, while the New York Times reported last week that Sen. Charles Schumer (D) is going to bat for Gillibrand, the New York Daily News reported Monday that he is not trying to clear the primary field for Gillibrand

In addition to Israel and Maloney considering the race, Manhattan Borough President Scott Stringer and Suffolk County Legislator Jon Cooper have already formed exploratory committees.

jeremy.jacobs@thehill.com