Four more Republican senators endorsed Ronald Reagan for president yesterday, and his campaign chairman predicted that all GOP moderates and liberals will fall into line when they realize he is electable.

The endorsements came from assistant Senate Minority Leader Ted Stevens of Alaska, Pete V. Domenici of New Mexico, Alan K. Simpson of Wyoming and Larry Pressler of South Dakota, who ended his own brief presidential candidacy in January.

Reagan now has been endorsed by 14 of the 41 Republican senators.

The four who announced support yesterday emphasized at a news conference that they do not expect 1980 to be like 1967, when conservative Sen. Barry M. Goldwater was overwhelmingly defeated by Lyndon B. Johnson.

The senators spent a half hour talking with Reagan by telephone Wednesday in a conference call arranged by Sen. Paul D. Laxalt of Nevada, Reagan's national campaign chairman.

All four emphasized that they chose to endorse Reagan because they are convinced of his electability against President Carter, and feel a need to head off any perception that a conservative cannot win the general election.

Vice President Mondale said yesterday that President Carter's winning streak in the primaries and caucuses results from the fact that his administration "is dealing with the problems that face America."

Speaking to several hundred jammed into the Buffalo, N.Y., City Hall lobby, Mondale noted that he has been campaigning in all parts of the country for Carter the past five months.

"There have been 17 elections," he said, "and in every election except one, President Carter has won."

Mondale said the only loss was the primary in Massachusetts, which he noted is the home state of Sen. Edward M. Kennedy, Carter's chief rival.

Mondale said Carter has done more than any other president to help the cities and to reverse the nation's dependence on foreign oil.

"No president in history, has been better for Buffalo and the surrounding community than Carter," Mondale said. "We have been at peace, we are at peace, and under President Carter we will stay at peace."

Republican presidential candidate George Bush yesterday said he questioned President Carter's reliance on Hamilton Jordan as a negotiator with the Panamanian government on medical treatment for the exiled former shah of Iran.

In a statement and news conference in Milford, Conn., Bush said that when "Jimmy Carter sends a domestic political aide to do a diplomat's job, he can hardly complain" about speculation that "the White House is playing politics with both the hostage crisis and the health of a man who, regardless of what critics of his regime may say, deserves humane medical treatmennt to stay alive."

Jordan has been reported in Panama discussing the shah's possible surgery with officials of the Panamanian government. Bush said he doubted that Jordan was "the proper emissary to send on a mission of that kind of sensitivity," because his experience "is purely and simply that of a Georgia political operative."