BAGHDAD, Iraq (CNN) -- The United States has signaled to Iraqi officials that it is seriously considering proposed changes to an agreement that would set the terms for U.S. troops in Iraq, an adviser to the Iraqi prime minister told CNN on Tuesday.
But Baghdad is still waiting for Washington's official response to the amendments before it can approve the agreement before the end of the year when a U.N. mandate on foreign troop presence expires.
The Iraqi government does not expect an official response until after Tuesday's U.S. election, the adviser Sami al-Askari told CNN.
Iraqi Vice President Tariq al-Hashimi said the Iraq-U.S. security deal should be put to the Iraqi voters.
"National referendum is the best consensus that could happen regarding the agreement," al-Hashimi, Iraq's Sunni vice president, said at a news conference on Monday. "The agreement should not pass without the approval of the Iraqi people."
Al-Hashimi noted that the agreement will directly impact the people of Iraq, and that is why they should vote on the matter.
"They should have the final word, and everyone else must listen and obey," he said.
U.S. and Iraqi negotiators recently agreed to the draft status-of-forces deal that would set the terms for U.S. troops in Iraq after the U.N. mandate on their presence expires at the end of this year.
But last week, Iraqi officials submitted several amendments to the draft plan to U.S. negotiators in Baghdad. Iraqi Foreign Minister Hoshyar Zebari told CNN that the proposed changes call for a fixed timetable of U.S. troop withdrawal; a specific number of sites and locations that would be used by the U.S. military; and Iraqi jurisdiction over U.S. forces who commit certain crimes in Iraq.
Zebari noted that some of the proposed amendments are simply "language clarification" that "are not essential."
White House spokeswoman Dana Perino said last week that any changes would have to pass "a very high bar" for the United States to consider altering the draft status-of-forces agreement, which she described as the "best offer."
The agreement must be approved by Iraq's Cabinet by a two-thirds majority before Iraqi Prime Minister Nuri al-Maliki can submit it to the Iraqi parliament for approval.
Jalal Deen Sagheer, a senior member of the Supreme Islamic Iraqi Council -- a key member of the ruling Shiite bloc -- said the agreement "is on the right track" but threatens to be derailed by Iraqi political blocs "who don't want to approve the treaty no matter what."
"Some Iraqi lawmakers want to embarrass Maliki and his government," Sagheer told CNN on Sunday. "Others just want him to fail even though they know very well that the Iraqi government is doing all it takes to guarantee Iraq's... interests and that the agreement will be based on Iraq's sovereignty.
"Still I believe that the main political forces in the parliament will either say 'yes' in a strong manner or 'no' in a strong manner."
The most vocal opponent of the security deal in Iraq has been the political party of radical Shiite cleric Muqtada al-Sadr, which opposes any U.S. military presence in Iraq.
Sagheer noted that most Iraqi lawmakers are "stuck between two fires."
"If the Iraqi politician agrees on signing the treaty, they would say he is an American agent," Sagheer said.
"And if he rejects it, they would say he is an Iranian agent. This is why I said the agreement is now on the right track and we are waiting for the American side to finish reviewing the amendments that the Iraqi government sent before they bring it to the Iraqi parliament."
The draft status-of-forces agreement, according to a copy obtained by CNN, calls for U.S. combat troops to be out of Iraqi cities and villages by July 30, 2009, and out of the country entirely by December 31, 2011. The agreement allows for an earlier withdrawal or an extension of the U.S. forces' stay in Iraq, by agreement of both parties.
It also allows the Iraqi government to ask "the United States government to leave certain forces for training and for support purposes for the Iraqi forces."
Zebari said Baghdad wants the proposed timetable "to be fixed without any optional conditions for further extension."
Legal jurisdiction over U.S. forces in Iraq has also been a sticking point in the negotiations, with the U.S side preferring that its troops and contractors remain immune from Iraqi law.
Baghdad had sought the power to arrest and try Americans accused of crimes not related to official military operations, plus jurisdiction over troops and contractors who commit major crimes in the course of their duties.
Zebari said Baghdad wants more clarification in the status-of-forces agreement regarding the issue of jurisdiction.
"U.S. military personnel and civilian components working with the military will enjoy American jurisdiction while they are in their bases and when they are on missions, combat missions and so on," he said. "But outside these two categories, here's the difficulties: Which jurisdiction would be applicable if a gross violation was committed, if a premeditated crime was committed?"
He noted that the draft agreement calls for a joint commission to be formed to determine the jurisdiction, but Iraq wants that changed to be entirely under Iraqi jurisdiction.
"So as you can see some of this may be difficult," he noted.
If the U.S. agrees to the proposed changes, Zebari said he expected the deal to be approved quickly.
"After these amendments I doubt there would be any further changes or amendments because nobody's interested to reopen, renegotiate the package again," Zebari said. "For months we've been negotiating that and I think what we have is almost the final draft."
CNN's Mohammed Tawfeeq, Saad Abedine and Phil Black in Baghdad contributed to this report.