Rice began her three-day Middle East trip with a visit to Baghdad on Sunday, where she said she was encouraged despite a recent surge in fighting.
Rice has been making the case that majority-Shia Iraq is an Arab state, with an Arab identity that deserves solidarity from its majority-Sunni neighbours.
The Bush administration is arguing that although Iran has influence inside Iraq, Sunni states nervous about Iran's spreading influence in the Middle East should not use that as an excuse to give Iraq the cold shoulder.
Few excuses
Speaking on Sunday in Baghdad, Rice challenged Arab states to respond to security improvements and political advances in Iraq, saying that there are now few excuses left for delay.
"There are some nations that don't recognise our political process and ... are inciting strife"

Nuri al-Maliki,
Iraqi prime minister

She said she would make the case that much has changed inside Iraq in the past year, in part due to the presence of additional US troops and also to what she says is growing political cohesion among Iraq's sectarian and ethnic factions.
"Adjustments are going to have to be made," in the way Arab states regard Iraq, she said.
Monday's developments came as six people died in clashes in Baghdad's Sadr City.
A police commander said the dead in the predominantly Shia district of the capital included three policemen and three civilians.
Four other civilians were injured in the fighting, according to the officer.
Al-Maliki's comments
For his part, Nuri al-Maliki, the Iraqi prime minister, who will attend the Kuwait conference, told The Associated Press news agency on Monday that he would speak frankly to Arab diplomats.
"There are countries that support the political process and are opening embassies here," he said, a reference to unfulfilled pledges from Saudi Arabia and Bahrain.
"We need the others to open embassies here, too. There are some nations that don't recognise our political process and ... are inciting strife. "I am bewildered by the position of these nations."