The Senate Finance Committee is scheduled to resume work on President Carter's proposed windfall profits tax bill today, amid prospects that it may run into some bitter in-fighting in trying to undo last week's tax-credit spree.

In the past 2 1/2 weeks, the committee has approved $99.2 billion in tax breaks for the 1980-90 period and has voted $25.2 billion in exemptions from the windfall tax -- using up $20.4 billion more than the windfall tax would raise.

On Friday, committee Chairman Russell B. Long (D-La.), embarassed by the outsized deficit, ordered staffers to prepare an alternative package that would trim back the tax breaks and raise "substantial" amounts of revenue.

However, there were indications almost immediately that the move could set off a fierce fight among various factions on the committee, pitting the proponents of the tax credits against those backing further exemptions and allies of major oil companies against those favoring independents.

The committee received a taste of that on Friday as senators from Northern and Southern states clashed over how to distribute the proposed aid to the poor designed to offset the recent rise in energy prices.

This week, in addition to the continuation of that battle, disputes already are brewing over how much more oil to exempt from the windfall tax, whether to favor large producers or small independents and which tax credits to pare back.

Sources say Long is likely to have a struggle on his hands to keep the panel in line and still meet his promise to the administration to complete work on the legislation promptly. Carter was told he would get the bill this month.

Meanwhile, GOP senators appeared likely to drop their earlier plans to try to block recent Internal Revenue Service rulings and regulations that would tighten rules on use of the foreign tax credit.

Although the Republicans were less than ecstatic about a pledge by Treasury Secretary G. William Miller last Friday to review the regulations, Long indicated then he personally was satisfied, making difficult any GOP attack.