Just 38 percent of Americans who have heard about the Iran nuclear agreement support it, while 48 percent of them disapprove, according to a new poll from Pew Research Center.

The stark number shows that the Obama administration could have a harder time than it thinks trying to sell the deal to the people's representatives in Congress over the next two months.

Obama has said the deal is not about trusting Iran, and instead is about getting Iran to stick to the new agreement aimed at curbing its nuclear program. But according to Pew, Americans still have major trust issues with Iran.

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A combined 73 percent of those familiar with the deal say they have no confidence (38 percent) that Iran will uphold the deal or have "not too much" confidence (35 percent).

A combined 54 percent of that same group says they have no confidence or not much confidence that the U.S. will be able to monitor Iran's activities appropriately.

Predictably, three-quarters of all Republicans in the poll oppose the deal, and just 14 percent approve. Among Democrats, 59 percent approve, and 25 percent disapprove.

Liberal Democrats are most approving of the agreement, at 74 percent.

The survey was conducted from July 14-20 among 2,002 adults, 1,672 of which had heard about the deal.