Debt ceiling: It's not over until the vote

Stocks plummeted on Sept. 29, 2008, when the first bank bailout bill was voted down -- a reminder of a risk lawmakers take if they push debt ceiling vote to the last minute.

NEW YORK (CNNMoney) -- The debate over the debt ceiling has fractured Washington, heightened partisan rancor and sowed seeds of distrust. And before all this ends -- leaders in Congress must garner enough votes to actually pass legislation.

The White House and congressional leaders have agreed to a plan to cut spending and raise the debt ceiling in time.

But final passage will require votes from both sides of the aisle, and they will have to be gathered at the last minute -- which heightens the risk of a miscalculation.

Witness what happened on Sept. 29, 2008, when the House at first rejected the $700 billion bank bailout bill.

Weeks earlier, Fannie Mae and Freddie Mac had been placed into conservatorship by the Treasury Department. Lehman Brothers had filed for bankruptcy. AIG Corp, the world's biggest insurer, had been bailed out by the Federal Reserve.

After all that, the Senate passed the bill. And then, as markets watched, the measure was voted down in the House -- a defeat that shocked investors and congressional leaders on both sides of the aisle.

Debt ceiling: What happens if Congress doesn't raise it?

Following the vote, the Dow slumped 778 points, in the biggest single-day point loss ever.

A few days later, the House reversed course and passed a modified version of the bill. Some 58 members switched their votes.

Why was the process so hard? A principal reason is that it was rushed.

Lawmakers who voted against the bill warned that "being stampeded" into a decision would be a serious mistake.

"Wall Street is so hungry for the $700 billion they can taste it. To get it they need to ... create panic, block alternatives and herd the cattle. We ask Congress not to rush," California Democrat Rep. Brad Sherman said before the vote.

That sentiment stretched across party lines.

"I am voting against this today because it's not the best bill. It's the quickest bill," Rep. Marilyn Musgrave, Republican of Colorado, told the New York Times. "Taxpayers for generations will pay for our haste and there is no guarantee that they will ever see the benefits."

Norman Ornstein, a resident scholar at the American Enterprise Institute, said lawmakers now face a similar situation.

Lawmakers aren't going to have a lot of time to consider their options. And the negotiations are happening behind closed doors, limiting the involvement of rank-and-file members.

"With TARP, it wasn't clear that another day or two wouldn't make a big difference," Ornstein said. "If you take two to three days messing around with this, you end up with what could be a profound and very long lasting impact."

Alabama Republican Sen. Jeff Sessions has voiced concern about the timeline, saying there is a "very real risk that no text will be available until the last minute."

And like 2008, not everyone is dealing with the same set of facts. At that time, every high-ranking government official from then-President Bush on down was warning of dire consequences if TARP faltered in the House.

That moved a few members into the "yes" column, but not all.

"We're on the cusp of a complete catastrophic credit meltdown. There is no liquidity in the market," Rep. Sue Myrick, a North Carolina Republican, said in a statement before the vote. "We are out of time. Either you believe that fact, or you don't. I do."

Right now, despite warnings from Treasury Secretary Tim Geithner, President Obama, Federal Reserve Chairman Ben Bernanke and even House Speaker John Boehner, a number of Republicans remain so-called debt ceiling deniers.

"You've got enough people out there, way too many people, who aren't going to be convinced until Armageddon actually happens," Ornstein said.