WASHINGTON — Prime Minister Benjamin Netanyahu of Israel has been reaching out to leading Capitol Hill Democrats to try to ease criticism over his coming address to Congress, but has made little progress.

Senator Harry Reid of Nevada, the Democratic leader, said Thursday that Mr. Netanyahu had called him the previous afternoon to explain why the White House had been circumvented before he was invited to speak before Congress. The prime minister has also called Representative Nancy Pelosi of California, the House Democratic leader, and Senator Charles E. Schumer of New York, the Senate’s No. 3 Democrat.

The calls came at a delicate time. Congress is split over whether to impose further sanctions on Iran as the United States and Tehran negotiate a possible freeze to its disputed nuclear program. President Obama has said any vote on sanctions would jeopardize the talks. Mr. Netanyahu, who is to address the issue in his congressional speech, and many pro-Israel lawmakers in Congress have urged a hard line.

Mr. Netanyahu’s office confirmed Thursday that he had called Democrats and “other friends” in Congress in recent days, and that he “reiterated that the survival of Israel is not a partisan issue.”