(CNN) -- The United States expects to bring a new resolution on increased sanctions against Iran over its nuclear program to a vote in the United Nations Security Council this week, and a U.S. official is warning that two key allies who do not support the resolution will "have to explain their vote."
In his daily briefing Monday, State Department spokesman P.J. Crowley said, "We expect to bring this matter before the Council this week."
Crowley would not specify a day but a U.S. official who has direct knowledge of the Iran sanctions resolution but is not authorized to speak for attribution told CNN the United States expects the U.N. Security Council vote will be Wednesday or Thursday of this week.
The United States "has not given up" on yes votes by Brazil and Turkey, two countries which oppose sanctions, but both nations have made it clear they are not about to change their minds, according to a senior administration official familiar with the resolution details.
The U.S. official, however, claimed "we haven't given up on anything. We are confident we have the votes to pass this resolution, but every country will have to make up its own mind."
Brazil has said the United Nations should give more time for Iran to fulfill its promise on a nuclear fuel enrichment deal that leaders of Brazil and Turkey reached with Iran in May.
"We expect that this matter will be brought to a vote this week and every country will have to stand up and decide what it stands for," the U.S. official said.
"For countries like Turkey and Brazil that are on the council the question is, are they going to affirm the importance of the international non-proliferation system or are they going to vote for a country that is not in compliance with its international obligations." said the official, revealing American frustration with its two allies. "These are judgments that every country will have to make."
The official added, "We're going to vote for the resolution and it will be up to other countries to decide what to do and to explain their vote. I don't think we ever expected the resolution to pass unanimously."