A proposed $14 billion federal bailout for the Big Three U.S. automakers died in the U.S. Senate on Thursday, raising questions over whether they'll be able to keep pledges to build a greener fleet of vehicles. But a last-minute move by the White House to step in with emergency assistance money could ease the automakers' worries.

Facing serious financial crises, General Motors and Chrysler have told Congress they would build more high mileage and energy-efficient vehicles as payback for federal assistance. Ford, which has said it is not in as dire financial straits as the other two automakers, has pledged to speed up development of battery-powered vehicles.

But Senate Democrats weren't able to overcome Republican opposition to get the required 60 votes to continue debate on the bailout Thursday night. That – along with the increasingly poor global economy and plunging oil prices – could put the Big Three's green plans in jeopardy.

The bailout's failure sent automakers' stocks down sharply in early trading Friday. But news that the Bush administration was considering tapping the Troubled Asset Relief Program (TARP), the $700 billion fund set up by Congress to aid the U.S. financial sector, to help the Big Three sent shares back up again, Reuters reported.

The Bush administration was considering such a step to "prevent a collapse of troubled automakers," according to White House spokeswoman Dana Perino.

Automakers have seen sales crash in recent months. General Motors' sales fell 41 percent in November while Ford, Toyota and Honda saw sales drop in the 30 percent to 32 percent range. GM and Chrysler could face imminent collapse without emergency funding, analysts have warned.

In seeking that funding, GM CEO Rick Wagoner had asked Congress earlier this month for an immediate $4 billion as part of an overall request of $12 billion in short term loans and a $6 billion line of credit to cope with a continued downturn in the market.

In return, he said GM would "launch predominantly high mileage, energy-efficient cars" in the next four years. On the hybrid and electric vehicle front, Wagoner said the anticipated 2010 launch of its hybrid Chevy Volt would be followed by up to 15 hybrid models by 2012, as well as a fleet made up of half flex-fuel vehicles that can run on mostly-ethanol fuel blends (see Chevy Volt Cleared for 2010 Production and Utilities Join GM to Promote Plug-In Hybrids).

Chrysler LLC Chairman and CEO Robert L. Nardelli had asked for a $7 billion bridge loan and pledged in turn changes including a new push to make "fuel-efficient cars and trucks that people want to buy."

Nardelli promised a 2009 fleet that would have 73 percent more fuel-efficient vehicles from this year, as well as the company's first electric-drive vehicle in 2010. By 2013, Chrysler wants to have 500,000 electric-drive vehicles will be on the road (see Chrysler Eyes 2010 for Launch of One of Three Electric Cars).

Ford President and CEO Alan Mulally told Congress that the company "does not anticipate a near-term liquidity crisis," putting it in a more secure position than GM and Chrysler. Still, Mulally asked Congress for $9 billion in emergency bridge financing to "continue our aggressive transformation and restructuring."

That included a pledge to release an electric van in 2010 and an electric sedan in 2011 for fleet customers, as well as more hybrids and all-electric cars for consumers in 2012 (see Ford Outlines Fuel Economy, Electric Car Plans to Feds).

Beyond the immediate problems facing the Big Three, they and other automakers could face even stronger headwinds when it comes to selling more fuel-efficient vehicles. While carmakers have seen overall sales decline, plummeting gasoline prices have put an even greater crimp on sales of hybrid vehicles, Green Car Congress reported. 

Sales of hybrids in November fell 50 percent from the same month last year to stand at 16,571 vehicles, little better than sales volume back in November 2005. That included a fall in sales of Toyota's market-leading Prius hybrid, which fell 48.3 percent to 8,660, a low not seen since January 2007.