Ronald Reagan said today that he "strongly" assumes he has won the Republican presidential nomination.

Reagan, at a news conference here, responded to reports that George Bush, his sole remaining GOP rival, was about to withdraw, but the former California governor based his claim not on the prospective withdrawal but on Bush's decision not to campaign in California. Reagan said this assured him of California's 168 delegate votes in the June 3 winner-take-all primary. United Press International currently credits Reagan with 989 of the 998 delegates needed to win the GOP nomination.

Reagan said he expects "full-hearted support" both from Bush and former president Gerald R. Ford, who is scheduled to host a Republican dinner in Lost Angeles Tuesday that Reagan is to attend. Both Bush and Ford have long promised to give their backing to the party's eventual nominee.

In Baltimore today, Ford said he would not accept an invitation to join a Reagan ticket.

"It is not at all predictable for my name to be considered among the vice presidential nominees," Ford said. "There are some good vice presidential possibilities. I hope one is selected."

Ford also said that Reagan might not be a Phi Beta Kappa, but "he has good sense and worked hard" as governor of California.