As talk about Iran swelled, plenty of pundits, officials and politicians rushed to put forth strategy tips. Many, including Bush Administration members, suggested keeping an invasion on the table. Last week, another U.S. aircraft carrier headed toward the Persian Gulf.

The deeper question here is whether the administration can make such a decision alone — while presidents typically lead on foreign policy matters, the Constitution gives Congress the power to declare war. The Democrat-controlled House and Senate aren’t likely to support any Bush military plan.

Sometimes, the executive branch can get around a hesitant Congress. As Supreme Court justice Samuel Alito once pointed out, a commander-in-chief can wage war in emergency situations. However, the Iran problem has grown slowly; barring a drastic event, this line of argument won’t help Bush and Co.

So rather than focus on the nuclear threat, the administration has played up Iran’s presence in Iraq. A week and a half ago, after U.S. forces detained six Iranians, Secretary of State Condoleezza Rice warned that “the United States is not going to simply stand idly by and let these activities continue.”

Rice has also claimed Iran supports “violent extremists who destroy the aspirations of innocent Lebanese, Palestinians and Iraqis.” This seems the bigger issue — even if U.S. officials send out a press release for every Iranian captured, very few insurgents come from Iran.

In a report (pdf) called “Iraq and Foreign Volunteers,” Anthony H. Cordesman of the Center for Strategic and International Studies found Iran “a major source of funding and logistics for militant Shiite groups in Iraq.” But he also cited a Saudi National Security Assessment Project analysis of 3,000 foreign fighters in Iraq; Iran is lumped in with “other countries” that contributed a combined 5 percent of them.

Particulars aside, all this Iran-in-Iraq talk worries Joseph Biden (D-Del. and chairman of the Senate Foreign Relations Committee), who fears the Administration could use an Iran-Iraq link to invade — Congress authorized war with Iraq, and the president could declare both invasions parts of the same war. Biden cautioned Rice that, by his interpretation, the Iraq authorization would not apply to Iran.

Rice declined comment. She shouldn’t have: No one literate in English could interpret the Iraq authorization to justify an Iran invasion, and by her own statements nukes, not Iraq, drive U.S. concerns about Iran.

Here is what the force authorization holds:

(a) AUTHORIZATION. The President is authorized to use the Armed Forces of the United States as he determines to be necessary and appropriate in order to

(1) defend the national security of the United States against the continuing threat posed by Iraq; and

(2) enforce all relevant United Nations Security Council Resolutions regarding Iraq.

The authorization is, beyond debate, a pre-war endorsement for invading Iraq and nothing more. It speaks of the threat posed by Iraq to the United States, not that of any country to Iraq. And Bush can enforce Security Council Resolutions “regarding Iraq.” This document can hardly be taken to guarantee a prolonged Iraq occupation — indeed, it doesn’t; Congress can pull funding — much less an invasion of Iran on the grounds of a threat to Iraq.

Speaking of that threat, the shift toward it, and away from nuclear weapons, is politically expedient but difficult for even Rice to keep straight. One sentence after alleging Iranian support for “violent extremists,” she tied U.S. policy to the nuclear program, and to the nuclear problem alone: “I repeat an offer that I’ve made several times, today. If Iran suspends its uranium enrichment — which is an international demand, not just an American one — then the United States is prepared to reverse 27 years of policy.”

Attacking Iran may or may not be the best possible move in this situation. But the administration will have to focus on the country’s nuclear ambitions, not the threat to Iraq, to convince Congress and the American people.