The US government has been criticised for granting a visa to former Iranian President Mohammad Khatami.
The US suspects Tehran of trying to build nuclear weapons
Some US politicians and a Jewish rights group have protested against the move, saying they consider Iran a threat to the country.
But former President Jimmy Carter is reported to be interested in meeting Mr Khatami, who is making a private visit.
The US state department said there were no plans for him to meet government officials.
The US granted the visa on Tuesday despite a looming showdown at the United Nations over Iran's nuclear programme.
Mr Khatami is to give a speech at Washington's National Cathedral on Thursday 7 September on the role that Islam, Judaism and Christianity can play in shaping peace.
He will also attend a conference at the UN on promoting dialogue.
The leader of the Middle East sub-committee of the House of Representatives is among those in the US opposed to Mr Khatami's visit.
"It is mystifying that we should roll out the red carpet to a person who has incited violence against civilians and who has expressed incendiary rhetoric against the United States and our allies," said Ileana Ros-Lehtinen.
The Jewish rights group the Simon Wiesenthal Centre has also criticised the visa.
"Granting former President Khatami a visa... will be viewed by the mullahs as a reward for their policy of confrontation and hatred toward the United States and her allies," the centre said in a statement on its website.
But the Washington Post reported that Mr Carter had agreed in principle to meeting Mr Khatami, and that the possible timing of a meeting was being worked out.
Diplomatic relations with Iran were cut under Mr Carter's presidency following the seizure of the US embassy in Tehran in 1979.
Mr Khatami will be one of the most senior Iranian figures to visit the US since then, apart from officials going to New York on United Nations business.
Mr Khatami was president of Iran from 1997 to 2005, when Mahmoud Ahmadinejad was elected.