President Barack Obama's diplomatic outreach to Iran could get harder.
Congress is moving forward with tougher economic sanctions to deter Iran from developing nuclear weapons.
The move comes despite the first contact between the two countries in more than 30 years.
At the end of July, a few days before the inauguration of Iranian President Hassan Rouhani, the House voted 400-20 to adopt the Nuclear Iran Prevention Act, legislation that increases existing sanctions.
Existing sanctions have already cut Iran's petroleum exports in half, but an overwhelming majority in the House wants to impose additional sanctions to increase pressure on Iran to halt its nuclear weapons program.
Still, no bill is expected to be finalized before November and that gives the White House only a few weeks to see whether Iran really changes course under Rouhani.