WASHINGTON — Sen. Charles Schumer was ready to discuss everything from gun control to drones during a press conference in his Midtown office Monday — except his position on the Iran nuclear deal.

“This is such an important decision that I will not let pressure, politics or party influence [me],” Schumer said, holding fast to his weeks-long insistence that he’s still in the decision-making stage.

Schumer has come under mounting pressure from opponents of the Iran agreement — including many of his Jewish allies — to vote against it next month in Congress.

One source said the normally thick-skinned senator — who is also feeling the heat from Democrats to back the deal — “exploded” during a meeting last week with about 60 Jewish leaders.

Schumer “lost it,” said the source.