Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) maintained yesterday he has an agreement within his party to keep such controversial "social issues" as abortion, busing and school prayer off the Senate floor until next year to hold the way open for President Reagan's economic program.

But party conservatives, many of whom ran for election on these very issues, quickly disputed this -- the first hint of a split in GOP ranks this year. "There will be a proper mix of issues this year," said Sen. Jesse Helms (R-N.C.), chairman of the Agriculture Committee. "The Senate won't spend all its time this year on the economy."

The agreement to postpone consideration of social issues until 1982 was approved by the executive committee of the party's Policy Committee two weeks ago. The motion carried unanimously, but Policy Committee chairman John Tower (R-Tex.) said that individual senators would not be bound by the resolution and that it didn't apply to offering amendments, according to committee minutes.

"My goal is to adjourn on Oct. 1 and we can't do that if we get involved in collateral issues," Baker told a breakfast meeting with reporters. "They are important issues, emotional issues, but they are next year's issues. I want this year to be Ronald Reagan's year."

"I have unanimous support in the caucus" on postponing floor debate, the Tennessee Republican added. "I can't stop people from offering amendments, but I'm sure going to try to keep them off."

The ban does not apply to commitee activity on social issues, Baker said. "I did not consult the White House on this. It was my initiative and I informed the president and he said he thought it was a good idea."

Baker has long been at loggerheads with many of the vocal and highly organized conservative groups lobbying for a social agenda that includes banning abortion and school busing, ending gun control and putting prayer back in schools.

Yesterday spokesman for several of these groups indicated they plan to press their causes and warned that any attempt to stop them will be met with widespread conservative opposition across the country.

"I just think Sen. Baker doesn't want to talk about these issues because every time he does he looks bad," said William Billings, executive director of the National Christian Action Coalition.

"Many of the new Republican senators weren't elected because of their stand on the economy," Billings added. "If people see this new conservative Congress isn't even going to talk about abortion, they aren't going to put up with it."

It was difficult to judge the split in GOP ranks over postponing consideration of social issues. Baker himself added to the confusion when he brought up the subject at the meeting with reporters. During it, he said that Republicans had agreed unanimously to the postponement at a meeting Wednesday of the Republican Conference, which includes all party members, and that conference chairman Sen. James A. McClure of Idaho had proposed it. There was, Baker said, "a lot of discussion but no opposition."

Later, however, the majority leader said he had made a mistake: the group was actually the executive committee of the Republican Policy Committee, a much smaller group; the meeting took place two weeks ago; and Tower, not McClure brought the matter up.

Several conservatives said they had never heard about postponing social social issues. "I'm not going to do that," said Senate Labor Committee Chairman Orrin G. Hatch (R-Utah). "If he [Baker] wants to do that I wish he'd gotten together with me. This isn't Baker's style. He has never tried to pressure me to do anything."

Others were confused about Baker's misstatements, and doubted the practicality of putting social issues on the back burner. "I have no objection to saying our first priority has to be the economy," said McClure. "But I'd have some hesitancy in saying we wouldn't deal with these other issues all year."