With gas lines spreading into more and more members' districts, House Democratic leaders are pushing for a vote in the next few weeks on new legislation on authorize a nationwide gasoline rationing plan.

The leaders - and much of the membership, too, judging from interviews - are confident that some rationing bill will be passed before Congress departs in early August for its summer recess.

That would be a remarkable turnabout, even for the unpredictable 96th Congress. Just six weeks ago, the House Rejected a Carter administration rationing plan by a resounding margin, an action that prompted an angry retort from the White House. President Carter said then he would leave the question of rationing to Congress.

But now Carter, too, has changed his mind. His aides have told congressional leaders that the president will put together a new rationing system quickly this summer if Congress gives him the authority.

Since the bipartisan Senate leadership favors a rationing plan, chances seem good that authorizing legislation will be adopted.

The administration's change of heart stems partly from the political pressure that gasoline lines have generated, and partly from a strong proo-rationing push from administration inflation fighters Alfred Kahn and Barry Bosworth.

Kahn and Bosworth have reportedly argued forcefully for gasoline rationing, saying that the current situation creates unstoppable upward pressure on prices and profit margins in the oil industry - pressure that will exacerbate the problems plaguing Carter's anti-inflation guidelines.

In a meeting with congressional leaders yesterday, Kahn and a top-level team of administration economists said that, even with gas rationing, the current 7 percent annual standard for wage and price increases will almost surely have to be raised in 1980.

The apparent reversal of mood in the House stems directly from the public's frustration with the current gas supply situation, in which a driver's access to gasoline is determined by his or her willingness to put up with short selling hours and, in many places, long waiting lines.

Under a rationing plan, the amount of gasoline each driver could buy would be reduced - sharply for some people - by some regulatory formula.

"The members are clearly getting the message that their constituents prefer legal rationing to gas line rationing," said Rep. John D. Dingell (D-Mich.), chairman of the House sub-committee that will consider rationing legislation.

"A lot of the guys who complained loudest when the plan was up a few weeks ago are now coming to me and begging for a new rationing bill," Dingell said.

He said his subcommittee will meet to write a rationing bill early next month. The most likely option, he said, is a short piece of legislation giving Carter authority ot impose a system - a system that would become law unless Congress rejected it within 30 days.

Another possibility is the "sticker plan" championed by Rep. Toby Moffett (D-Conn) in which every car would bear a sticker listing one day of the week. The car could not be driven on that day.

Moffett says this would reduce total gasoline consumption by one-seventh, or about 14 percent - somewhat above the level of the current supply shortage.

The rationing authority that people in Congress are talking about would be "standby" authority - to be invoked only in the case of a severe national shortage, such as another Arab oil embargo. But Dingell noted yesterday that "everybody is now a lot more willing to believe that that kind of shortage might hit. Everything about the oil situation seems to get worse every month."