A Democratic senator on Monday introduced legislation that in some cases would deny funding for the Bush administration to take military action against Iran without first getting congressional approval.

Sen. Jim Webb, D-Va., has long argued that Iran must be part of a regional solution to end the war in Iraq, and has repeatedly voiced concerns over the fact that the Bush administration deems the 2002 congressional resolution authorizing force in Iraq applicable to Iran.

"This presidency has shot from the hip too many times for us to be able to trust it to act on its own," Webb told reporters Monday. "It's not the way the Constitution was designed. We need Congress to be involved in any decision to commence military activities absent an attack from the other side or a direct threat."

"What I'm saying today is, clearly, that we should not give up any of our positions diplomatically, with respect to Iran, but I believe it is not in the power of the president himself to decide to take unilateral military action there," he added.

If enacted, Webb's bill would ensure that "no funds ... may be obligated or expended for military operations or activities within or above the territory of Iran, or within the territorial waters of Iran, except pursuant to a specific authorization of Congress."

The bill has a number of exceptions, however. The proposal would allow military action under the following scenarios without prior congressional authorization:

— When the action is aimed at repelling an attack launched or about to be launched from inside Iran;

— When military forces are in "hot pursuit" of enemy forces fleeing into Iran; and

— When the military is supporting intelligence gathering.

The bill would require the president to submit a report to Congress within 24 hours justifying any spending that would support any of the exceptions.

Webb told FOX News last week that his concern came about when he compared the 2002 authorization to go to war in Iraq with the presidential signing statement accompanying it clarifying prerogatives the administration deemed permissible under the authorization.

He said the ambiguity in the signing statement leaves room for the president to interpret the authorization as authorizing war with Iran. And, Webb said, according to the signing statement, the president retains the right to take military action "to respond to threats against American military interests."

Webb appears to have support from Democratic lawmakers. Senate Majority Leader Harry Reid said last week that he had not read the amendment, that would be attached to a supplemental war spending bill, but is "very, very confident ... in real generality ... that I can support" Webb.

Webb said he believed his amendment would have a good chance of passing if it is added to the spending bill because it would be tied to the must-pass appropriations measure. Its future, however, will depend a lot on work to be done later this month by the Appropriations Committee.

Following complaints by congressional Democrats over the past few months, Webb told "FOX News Sunday" early last month that the administration is not doing enough to engage Iran diplomatically to prevent its interference in Iraq.

"What the administration is doing right now is playing up Iranian participation in order to try to drive the stakes up to the extent that we don't deal with Iran. Now, yes, Iran's definitely, from everything that I can see, playing in some way inside Iraq. And tactically, as a former Marine, in the places where Iran is definitely playing, they should be dealt with," he said.

But, Webb continued, "the situation that we have right now where we continue to talk only about the military side — again, it's half a strategy."

Last week, Joint Chiefs of Staff Chairman Peter Pace told lawmakers that the United States is not planning any attacks on Iran. The Bush administration also announced that it will attend a regional conference on Iraq in which Iran and Syria are invited to participate.

None of that appears to have eased Reid's concerns.

"There are many out there much smarter than I am who believe the administration is ramping up to have the same thing happen in Iran that happened in Iraq," he said.

FOX News' Trish Turner contributed to this report.