(CNN) - Almost two-thirds of Americans -- 63 percent -- believe that the U.S. should not withdraw from the agreement made with Iran to prevent the country from developing nuclear weapons. Only 29 percent believe the U.S. should withdraw, according to a new CNN poll conducted by SSRS.
President Donald Trump is expected to announce Tuesday whether he will remove the U.S. from the deal, which lifted some sanctions in exchange for curbs on Iran's nuclear program. Trump has repeatedly criticized the agreement, which was made under former President Barack Obama, as a bad deal and has threatened to pull out the U.S. even though Iran has been certified by a UN organization as complying with the terms of the pact.
The strongest proponents of withdrawing from the treaty are Republicans (51 percent say the U.S. should withdraw), conservatives (47 percent) and those who approve of the job Trump is doing as president (46 percent).
Support for remaining in the agreement comes even as a strong majority of 62 percent say they believe Iran has violated the terms of the agreement. Nineteen percent said Iran has not violated the terms, with the same share saying they have no opinion.
Those who approve of the way Trump is handling the presidency (80 percent) are apt to say Iran has violated the agreement's terms, while Democrats (30 percent) are most likely to say Iran has not violated those terms.
Almost 4 in 10 -- 37 percent -- say they approve of the way Trump is handling the U.S. relationship with Iran, while 46 percent disapprove. A sizable 17 percent have no opinion.
Positive takes on Trump for his handling of Iran are not as high as they are on other comparable issues, especially among his base. While 82 percent of Republicans approve of the way the President is handling foreign affairs, only 73 percent approve of his handling of the U.S. relationship with Iran.
At the same time, the percentage of people saying Iran poses a serious threat to the United States has ticked up since last year. Seventy-five percent say Iran is either "a very serious threat" or "a moderately serious threat", compared with 69 percent in October and 71 percent in August.
The share who consider Iran a "very serious threat" has increased 10 points since October -- from 30 percent to 40 percent. That's a high during the Trump presidency and about on par with the threat level seen in April 2015, around the time the framework for the nuclear deal was agreed on.
That increase comes across party lines, but Republicans continue to see Iran as a "very serious" threat in greater numbers (54 percent) than independents (35 percent) or Democrats (35 percent).
While perceptions of Iran as a threat are on the rise, the same measure is dropping on North Korea. Eight in 10 say North Korea presents a threat to the US, down from 86 percent who said so in October. Seventy-eight percent say Russia poses a threat, and 65 percent say the same about China.
The CNN Poll was conducted by SSRS May 2-5 among a random national sample of 1,015 adults reached on landlines or cellphones by a live interviewer. Results for the full sample have a margin of sampling error of plus or minus 3.6 percentage points, it is larger for subgroups.
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