About 90 lawmakers and government officials are taking part in the sit-in in parliament. Yesterday, about 80 deputies walked out of the parliament session to protest a decision by the conservative Guardians Council to ban many reformist candidates from running in parliamentary elections on 20 February.
The head of Iran's main pro-reform party, the younger brother of the Iranian president, Mohammad Reza Khatami, is among the vetoed candidates.
Iran's supreme leader said today that the row between reformists and conservatives must be resolved through legal channels. However, he said he would intervene if the impasse could not be settled legally.
Bill Samii, RFE/RL's regional analyst on Iran, says it's likely the supreme leader will ask the Guardians Council to reverse at least part of the ruling.
"I think the most likely thing is that the supreme leader will call for -- perhaps in a behind-the-scenes deal -- he would call on the Guardians Council to reverse some of its decisions," Samii said.
Iran's 27 provincial governors have threatened to resign in a week if the ban is not reversed. The governors are responsible for organizing the elections in their areas.
Reformist leaders are threatening to boycott the vote if their candidates are disqualified. But Samii says such a boycott is unlikely since the legitimacy of the Islamic republic could be questioned.
"I don't think [a boycott] is very likely because president [Mohammad] Khatami and the speaker of parliament, [Mehdi] Karrubi -- although they've objected to the hard-line action -- they've really encouraged people to participate in elections. I think they see that as sort of legitimizing the revolution and legitimizing the Iranian political system," Samii said.
The Interior Ministry, controlled by reformers, yesterday called the Guardians Council decision illegal and said it would not be enforced.
Reformists say by eliminating their candidates the Guardians Council is trying to ensure that the conservatives will have the majority in the next parliament. Mashaollah Shamsolvaezin, a prominent journalist in Tehran, says he thinks the Guardians Council is trying to achieve this goal by reducing public participation in the elections.
"The Guardians Council is trying or wants its action to result in a decrease in participation in future elections so that the conservatives will win in the elections and take control of the parliament and, as a result, also take control of the government in the future," Shamsolvaezin said.
Such a tactic could work if the experience of last year's local election is repeated. Only about 20 percent of voters turned out for that election and the conservatives emerged as winners.
Shamsolvaezin says the conservatives may also be trying to show the world their discontent with the reform movement.
"The other message of this action is for the international community, saying that the conservatives are against the reforms of President Khatami's government and the reform movement in general and the situation should be reversed as it was before the victory of the reformists in the elections," Shamsolvaezin said.
Today in Tehran, visiting EU Foreign Policy Chief Javier Solana said Iran was facing international scrutiny after only about half of the 8,200 candidates were approved to stand in the elections.
Solana said, "it would be hard to envision our dialogue continuing with the same intensity if hard-liners are in power and had taken power in such questionable circumstances." He said a conservative victory could put EU-Iran dialogue "back to square one."
Samii says undermining Iran's improving international relations could be one of the conservatives' goals in banning reformist candidates.
"I think in the short term, this is going to harm Iran's relationships with other countries. I mean, under these circumstances, how can any country say that Iran is a democratic state and it's becoming more democratic? In fact, you know it's possible that for the hard-liners, for the conservatives, this is something that they want. A lot of them do not like relations with Europe and with the United States," Samii said.
Iran' main reformist party, the Participation Front, has asked political activists, intellectuals, journalists, and students to gather today at its headquarters in Tehran in protest.
It's not yet clear how successful protest efforts will be. Some say the deputies are only protesting their own disqualifications -- and not the overall flaws in the election laws. They add that the general public remains apathetic following a failure by reformists to fulfill their earlier promises.