The Senate talked through a second day on the natural gas pricing compromise yesterday while both sides fought for the bloc of undecided votes that will decide the multi billion-dollar issue.

From all accounts it is still very close. Senators who have announced a position are almost equally divided; positions of about 20 are not known or firm.

The issue is complicated because two important votes may be taken before the Senate gets to the merits of the compromise to end federal price controls on newly discovered natural gas by 1985.

Opponents are expected to try first this week or early next, depending on the number of absentees - to recommit the compromise to the House-Sening by some opponents that this top-priority legislation should not be killed by such an oblique blow.

If the motion fails, supporters would try to get the 60 votes needed to limit debate and get a final vote on the bill. Minority Leader Howard H. Baker Jr. (R-Tenn), who opposes it, said yesterday he expected the recommital motion to fail and the cloture motion limiting debate also to fail. If that happened the bill would die in a filibuster[TEXT OMITTED FROM SOURCE].

But Henry M. Jackson (D-Wash.), floor manager of the bill, said he was confident that the Seante would vote cloture, that enough members would not want to kill President Carter's No. 1 priority bill by filibuster.

Carter is making an all-out fight for the gas bill. Though a far cry from his original proposal to continue price controls at higher levels, it is the only major piece remaining of the massive energy bill he sent Congress 17 months ago with the goal of saving energy and reducing reliance on foreign oil.

Sen. Dale Bumpers (D-Ark.), who had helped write the compromise but became a question mark when it appeared the White House had made a deal to increase its breeder reactor program in exchange for a needed signature on the conference report, announced support for the measure.

Bumpers said he will make his fight against the breeder reactor on other legislation. Meanwhile, he said, though he favors continued regulation of gas he supports the compromise as a needed first step in fashioning an energy policy.

Gas prices will go up whether the bill passes or not, said Bumpers. The bill, he said, has the virtue of giving some protection to residential consumers by imposing first price increases on industrial consumers and by moving more gas from intrastate to interstate markets where shortages have occurred. It would do so by extending controls to gas consumed in states where produced.

Sen. Gary Hart (D-Colo.), who had voted earlier for continued regulation, also announced support for the compromise. He said that if the producer-consumer labor-business lobbies who oppose the bill for opposite reasons could come up with a workable substitute he would oppose the compromise. But since they haven't, he said, he would vote for the bill because it "does what needs to be done."