George Meany, president of the AFL-CIO, and John P. Sears, manager of Ronald Reagan's 1976 presidential campaign, don't agree on many things. But both said yesterday that President Carter has more to worry about after Tuesday's election than he thinks.

Meany, at an interview with a group of reporters, said reverse for Democrats in several key states made it doubtful Carter could win the 270 electoral votes needed for victory in 1980.

And Sears, in an interview following a talk to the Public Affairs Council, a group of corporation officials, underlined exactely the same point saying, "If I were Carter, I'd be worried to death."

Both men noted that in winning election last time, Carter received 89 of his 297 electoral votes in four states - Ohio, Pennsylvania, Texas and Wisconsin - where his share of the popular vote was barely 51 percent.

The loss of any two of those states would have given the election to then President Ford.

Pennsylvania, Texas and Wisconsin all replaced Democratic governors with Republicans on Tuesday and the GOP made a net gain of five House seats in those three states.

Ohio reelected Gov. James A. Rhodes (R), despite a determined Democratic effort, strongly backed by personal appearances from Carter and Vic President Mondale, to replace him with Lt. Gov. Richard F. Celeste (D), an early Carter supporter in 1976.

The president told his press conference in Kansas City that "I think there was a general expression of approval around the country of the Democratic Party and its policies." But he conceded that "we lost some very key races, some of them in the Midwest."

Sears noted that Republicans now are guaranteed control in 1980 of the governorships of "all the states ringing the Great Lakes, from Pennsylvania out to Minnesota.

"Of those states," he said, "Carter carried Pennsylvania, Ohio and Wisconsin by the skin of his nose, and Minnesota by a larger margin, because he had Mondale on the ticket." The other states in the area - Michigan, Indiana and Illinois - went for Ford.

"The Democrats are shattered now in Minnesota," Sears aid, noting that Republicans had won both Senate seats and the governorship on Tuesday. "Carter is in bad shape in the West and he's certainly no stronger in the South, so he looks to me like he's in trouble."

Meany, if anything, was more bearish on the president's prospects, saying he came out of the election "very poorly."

"If the election were today, I don't know how he could win New York," the AFL-CIO president said. "Pennsyvania doesn't augur well for him. No one can say he'd be guaranteed to get Minnesota or Wisconsin. If he loses a couple of those, where does he get 270 electoral votes? Ohio and Delaware are doubtful now. There's no indication he's any stronger now in the West than he was in 1976. Just take one big state away from him . . ."

Meany added, however, that the opposition might save Carter. "From my experience," he said, "the greatest thing Carter has going for him is the Republicans."

Meantime, liberal groups were looking worriedly at the list of senators who will be up for election in 1980 and wondering if the loss could be as severe as it was last Tuesday, when five leading Democratic liberals went down to defeat.

Half the 34 senators up for elections in 1980 are considered in the liberal camp.

Among them are Democrats Birch Bayh of Indiana, Dale Bumpers of Arkansas, Frank Church of Idaho, Alan Cranston of California. John C. Culver of Iowa, John A. Durkin of New Hampshire, Thomas F. Eagleton of Missouri, John Glenn, of Ohio, Gary Hart of Colorado, Ernest F. Hollings of South Carolina, Patrick J. Leahy of Vermont, George S. McGovern of South Dakota, Gaylord Nelson of Wisconsin, Abraham A. Ribicoff of Connecticut and Adlai E. Stevenson of Illinois.

This year, Republicans took over Democratic Senate seats in the home states of Culver, Durkin, Hart and McGovern.

Liberals are also worried about two of their Republican allies, Sens. Jacob K. Javits of New York and Charles McC. Mathias Jr. of Maryland, who could be subject to serious conservative challenges in their own party primaries.