Democrats may bring to the Senate floor this year a set of thorny conservative social issues that Republicans want to postpone until 1982, Senate Minority Leader Robert C. Byrd (D-W.Va.) said yesterday.

Republicans want the delay so that the issues -- among them abortion, capital punishment and school prayer -- will come up during an election year, Byrd said. He pointed out that the "far right seized on" these same issues in 1980 and used them to defeat a number of prominent Senate Democrats.

"I have a feeling some of those ghosts will be resurrected," Byrd said. "Some of the members on my side may want to set the record straight."

Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) said last week that he has an agreement within his party to keep emotional social issues off the Senate floor this year so they would not divert attention from President Reagan's economic program.

Several conservative Republicans quickly disputed this, and yesterday Byrd said he doubted Baker will succeed in enforcing any such ban. Byrd said, "If social issues are important in an election year, they are important this year."

However, Byrd said he didn't see any major split developing among Senate Republicans and he praised Baker's ability to enforce party discipline during a a series of votes last week that appeared to leave Democrats in disarray.

"The Republicans are standing together and they are outmaneuvering the veterans; they are outmaneuvering the school children; they are outmaneuvering the old people," Byrd said.

In the process, he all but conceded defeat in the Senate battle over Reagan's proposed budget cuts. In a bitterly fought floor fight Friday, Democrats were maneuvered into cutting $200 million from foreign aid so that they could use the money to restore part of the $1.6 billion cut from the federal school lunch program. Democrats then were defeated when they tried to restore $104 million cut from veterans' programs.

Republicans, Byrd said, also may be able to defeat a series of amendments the Democrats intend to offer this week to restore money for elderly people, subway riders, economic development programs and parents seeking loans for college students.

But the Democratic leader warned that the cuts will come back to haunt Republicans. Americans, he said, eventually will feel the pain of the cuts and "will know who inflicted it."

"The fetish of the moment may be numbers on a scratch pad," Byrd added. "Our concern is the people, and keeping them from falling through the safety net."