Senators of both parties have adopted a wait-and-see posture following the House’s stunning midday defeat of a $700 billion Wall Street financial rescue package, but many warned that a failure to act in the next few weeks could have catastrophic consequences for the economy.

“Our intention here is to wait and see what they do. We’re prepared to work with them as we have been because the problem is far too serious,” Senate Banking, Housing and Urban Affairs Chairman Chris Dodd (D-Conn.) said. “This isn’t some minor piece of legislation. This is as big a moment economically as our country has been in in decades, and we cannot leave town. If we have to stay here this week and next week, we’ve got to respond. Hopefully, nothing so cataclysmic would happen in between that would make whatever we do moot.”

Dodd said he did not anticipate the Senate trying to pass the bill unless the House reconsiders it and passes it. If the House had passed the plan, the Senate was expected to overwhelmingly approve the bill with 70 or more votes.

Republican supporters of the plan were equally determined to soldier on.

“I just don’t see how this can die with that vote,” said Sen. Johnny Isakson (R-Ga.), a supporter of the plan. “These problems in the credit market that are now beginning to hit Main Street are now going to mushroom. And there is a point in time where what you do … becomes inconsequential because too many things take place, and I think one of the problems here is the inability to get the clarity on the point that we’re at” in our economy.

Majority Leader Harry Reid (D-Nev.) indicated he believed Republicans will bear the brunt of the political blame for the failure of the bill in the House.

“I feel terrible for the Republicans,” he said as he ducked out of a Senators-only caucus. He canceled a planned news conference and said he was on his way to call Speaker Nancy Pelosi (D-Calif.).

Most Senators said they were scratching their heads for answers.

Asked if it was safe to say Senate Democrats were surprised by the House vote, Sen. Byron Dorgan (D-N.D.) smiled and said: “Generally, that’d be fair.”

Dorgan, who said he learned of the House vote via BlackBerry, agreed the Senate’s options were limited. “At this point, no one knows exactly what the next step is — we just learned the issue failed in the House.”

Senate Republicans, even those who were wary of the bill, seemed similarly shocked by the House action. They, too, said they had few suggestions for how the Congress would address the matter before Rosh Hashanah kicks off at sundown this evening.

Sen. Sam Brownback (R-Kan.), a conservative who had concerns about the bill, said the House decision underscores the need for more time on a $700 billion package. Describing the rejection as “high drama,” Brownback said, “this is the sausage-making process. We just had a bad first batch.”

Asked if the markets could sustain a gestation period, Brownback said: “If that’s the only option to get it right — yes. You have to.”

Senators said they knew the House vote would be close, saying they had gotten word that only 30 House Republicans were solidly behind the bill as of last night. In the end, more than twice that many sided in favor of the package but not enough to carry it over the finishing line.

President Bush put his weight behind the measure, both in a televised address this morning and in phone calls to House Members. Vice President Cheney also made calls. But none of that seemed to sway lawmakers in their party, a signal that the White House no longer has the muscle to influence Republicans with just weeks to go before a new president is elected.

One Republican Senator said the reaction of the market over the next few days could prompt House Members who voted against the bailout to reconsider, but that by Thursday it could be too late for the measure as crafted to have the impact the administration hoped for.

“This whole thing is like a plane going into a spiral dive. The deeper we get into the spiral, the harder it is to get out,” the Member said. This lawmaker, who had also been in contact with a number of House Republicans before Monday’s vote, described them as “irrational” and unwilling to consider almost any proposal. “There was nothing you could have put out there that they would have accepted,” the Republican Senator said.

Finance ranking member Chuck Grassley (R-Iowa) said he was surprised by the House vote and speculated negotiators might have to rework the proposal to include more private-sector involvement. “I think what they’ll have to do is satisfy more Republicans with a more private-sector solution,” Grassley said. However, Grassley agreed that if the markets continue to reel over the next several days it could change how some Members feel. “That could make some folks reconsider their positions,” he said.