The Resolution in question is [link|http://thomas.loc.gov/cgi-bin/query/z?c110:H.CON.RES.21:|here]. It expresses the sense of the House. It's not legislation.
[lots of whereas-es]
Whereas, on August 3, 2006, in a speech during an emergency meeting of Muslim leaders, Iranian President Mahmoud Ahmadinejad stated that the Middle East would be better off `without the existence of the Zionist regime', called Israel an `illegitimate regime' with `no legal basis for its existence', and accused the United States of using Israel as a proxy to control the region and its oil resources;
Whereas Iran funds, trains, and openly supports terrorist groups, including Hamas, Hezbollah, and Islamic Jihad among many others, that are determined to destroy Israel;
Whereas, on December 14, 2001, the President of Iran's Expediency Council, Ali Akbar Hashemi-Rafsanjani, threatened Israel with nuclear attack, saying, `[i]f one day, the Islamic world is also equipped with weapons like those that Israel possesses now, then the imperialists' strategy will reach a standstill because the use of even one nuclear bomb inside Israel will destroy everything [in Israel], while it will merely harm the Islamic world';
Whereas Iran has aggressively pursued a clandestine effort to arm itself with nuclear weapons; and
Whereas the longstanding policy of the Iranian regime is aimed at destroying the democratic State of Israel, the only democracy in the Middle East and the most important strategic ally of the United States, which is confirmed by statements such as those made by Iranian President Ahmadinejad and Council President Rafsanjani, demonstrating the threat of a nuclear-armed Iran: Now, therefore, be it
Resolved by the House of Representatives (the Senate concurring), That Congress--
(1) condemns, in the strongest terms, Iranian President Mahmoud Ahmadinejad's offensive remarks, contemptible statements, and reprehensible policies aimed at the destruction of the State of Israel;
(2) calls on the United Nations Security Council to charge Iranian President Mahmoud Ahmadinejad with violating the 1948 Convention on the Prevention and Punishment of the Crime of Genocide and Article 2, Section 4, of the United Nations Charter;
(3) further calls on the United Nations Security Council and all Member States of the United Nations to consider measures to prevent Iran from obtaining nuclear weapons, which would be both a dangerous violation of the Nuclear Non-Proliferation Treaty and a potential means to the end of carrying out President Mahmoud Ahmadinejad's threats against Israel; and
(4) reaffirms the unwavering strategic partnership between the United States and Israel and reasserts the steadfast commitment of the United States to defend the right of Israel to exist as a free and democratic state.
It had [link|http://thomas.loc.gov/cgi-bin/bdquery/z?d110:HC00021:@@@L&summ2=mcosponsors|103 co-sponsors]. I haven't seen a breakdown by party; I see a few rather prominent members of each party.
An awful lot more would be required for the Congress to advocate or authorize an attack on Iran.
The Resolution doesn't seem to be getting much attention yet (Google lists [link|http://news.google.com/news?tab=wn&client=firefox-a&ie=UTF-8&oe=utf-8&rls=org.mozilla%3Aen-US%3Aofficial&ncl=1117478931&hl=en|10 news stories]), even though it was passed on the 20th and was introduced in January. I read it as an appeal to the UN, not a statement that we're going to jump in if Iran doesn't change policy soon.
Of course, [link|http://www.washingtonpost.com/wp-dyn/content/article/2006/04/14/AR2006041401907_pf.html|the Pentagon has been war-planning Iran since 2003], if you believe William Arkin. Conventional wisdom is, though, that we don't have enough troops to go to war with Iran.