President Reagan's top two aides have suggested more firmly than ever that he will seek a second term, with a decision made in late summer and an announcement this autumn.

White House chief of staff James A. Baker III said in a speech Wednesday night in Houston that the president will make an announcement after Labor Day and that the decision will "gladden the hearts of his admirers around the country."

And presidential counselor Edwin Meese III told reporters yesterday that if Reagan "had to make the decision today he would definitely plan to run," and that circumstances are unlikely to change that outlook by summer.

Despite these hints that Reagan will be a candidate in 1984, the president has not yet decided, according to presidential intimates. They said one indication of this is his refusal to sign an authorization allowing supporters to set up an official exploratory campaign organization.

"In the past he has not been comfortable letting the organization get ahead of his decision," said one of Reagan's close political advisers. "The president has his own calendar, and the announcement won't be until fall, and it could be late fall."

Regardless of the calendar, however, many of Reagan's political supporters and Capitol Hill allies have been pressing for signals that he will seek another term. Reagan has responded with tantalizing hints that he will run but nothing that could be called a commitment.

"I will say quite candidly among most of us who are working with him there is a general feeling that he will run and in any event--whether he runs or doesn't run--you have to act as though he is going to run so as not to preclude that possibility," Meese said at a breakfast meeting with reporters.

The conventional wisdom among White House officials is that, barring unforeseen problems, Reagan will reach a final decision at his California ranch in August and announce his candidacy after Labor Day. Reagan made his official entry into the 1980 campaign in November, 1979, becoming the last of the GOP candidates to announce.

Even while Reagan ponders the decision this spring and summer, his aides and political operatives are laying the groundwork for a campaign. The president recently kicked off a series of luncheons for 1980 GOP supporters, and a group of regional political directors from the last campaign has been invited to the White House next week.

Also, The Wall Street Journal reported yesterday that Reagan promised Jordan's King Hussein at the White House last December that "we'll be partners for the next six years." A White House official last night denied that Reagan had said this.

Asked yesterday what Reagan would base his decision on, Meese said: "It will be based on his feeling that there still is work to be done, and I think it is pretty clear that there is, and that he can continue to make progress in these directions, and I think that personally he will feel that he can." He added that "I don't think there's going to be much this summer, when he makes this decision, that isn't apparent now."

Baker's hint of Reagan's decision came in a speech to about 900 people at the Forum Club in Houston, but he made no other comment on the matter.

Meese said that public opinion polls would be a factor in Reagan's decision only if "the president totally lost credibility with the American people--if something like that, where he would feel there was no way he could be an effective leader of the people--but I don't see any signs of that happening either."

Yesterday, White House officials released the results of two surveys done for Reagan by pollster Richard Wirthlin indicating that support for the president's goals increased after his recent speeches on the military budget and arms control.

Wirthlin did one survey March 17-21, before Reagan's March 23 televised speech on defense and a futuristic anti-ballistic missile system, and another survey April 7-10, after Reagan's arms control and defense speech before the Los Angeles World Affairs Council.

In the first survey, 35 percent of those who responded favored more defense spending, while 46 percent wanted less. In the second survey, 43 percent wanted more defense spending, while 41 percent wanted less.