A weary President Carter returned to the campaign trail yesterday to blast Republican tax-cut proposals and promise a complete cleanup of the "mess" he said he inherited in the General Services Administration.

Fighting fatigue that had his aides openly expressing concern. Carter received bouquets for his Camp David diplomacy from politicians and citizens and praised Democratic congressional and gubernatorial candidates in Pennsylvania and Ohio.

He continued to express optimism on the future of the Middle East negotiations but said that critical comments from Jordan's King Hussein might limit the progress in dealing with the Palestinian question.

In Columbus, Ohio, last night, Carter told a Democratic Party dinner that "very shortly, after the Knesset [the Israeli parliament] votes, we will see a peace treaty between Israel and Egypt that will last."

A Democratic Party official traveling on Air Force One said the president is "so darn tired we're just trying to keep him from blowing up."

Carter has had no break in his schedule since the 13-day Camp David meeting ended last Sunday. He complained several times of his fatigue to political audiences in North and South Carolina on Friday night.

Nonetheless, he endured the rituals of a town meeting in this steel city north of Pittsburgh - including the now-customary little girl's hug and an unexpected invitation to become an honorary member of a local Girl Scout troop.

The crowds, as they had been in the Carolinas, seemed unusually demonstrative and friendly toward the President.

Carter used a question on senior citizen property tax relief to tee off on the Republicans' main campaign issue for 1978 - the Kemp-Roth bill calling for a 33 percent tax cut over the next three years.

Any revenue reduction that "drastic," he said, would either cut essential government services or throw an added burden onto the local property tax.

"I believe we can cut taxes substantially," Carter said, predicting that Congress will send him a bill calling for a $20 billion reduction in current levies. But to do what the Republicans have been advocating in a cross-country "tax clipper" aircade with their most prominent national spokesmen would "inevitably mean adding to the property tax burden," Carter said.

He also sought to blunt what some Democratic leaders fear may become a political backlash on the GSA scandals by putting the blame for contracting and purchasing frauds in the giant agency on predecessor Republican administrations.

"What has happened there over the last decade," he said, "has amounted to hundreds of millions of dollars stolen from you, the taxpayers of our country . . . We inherited a mess, but we are getting it under control."

The Pennsylvania and Ohio trips put Carter's endorsement behind a pair of gubernatorial candidates who gave early support to his drive for the 1976 presidential nomination and who could be important allies in 1980.

Here, he praised former Pittsburgh mayor Peter F. Flaherty, who served for a year as deputy attorney general in Carter's administration before coming back to win the Democratic gubernatorial nomination. Flaherty is leading Republican nominee Richard L. Thornburgh, also a former prosecutor, in both parties' private polls.

At a fund-raising dinner in Columbus last night, Carter gave his blessing to Ohio Lt. Gov. Richard Celeste, a Democrat, who is believed to be running a close gubernatorial race against the Republican incumbent, James A. Rhodes.

In an interview with out-of-town editors released by the White House yesterday, Carter said, "I don't see any trend at all against Democrats this fall," and predicted that the party's losses in the House will be "much less" than the 35 to 40 seats he said had been typical of midterm elections in the past.

That prediction is shared by politicians of both parties and is supported by public opinion polls.

In the same interview, Carter minimized the political significance of the primary election defeats of two prominent Democratic liberals, Massachusetts Gov. Michael S. Dukakis, who was seeking renomination, and Rep. Donald M. Fraser, who sought a Democratic senatorial nomination in Minnesota.

Carter said special factors were at work in both states and "I don't see it as a trend in the future."

In that interview and in the town meeting here, he again ruled out resorting to direct wage-price controls "unless our country reaches an extreme emergency." He said the new guidelines for wage and price increases now being prepared by the administration "will be a tough, strong step against inflation." But he gave no hint of the timing or substance of the new guidelines.

Carter also told the editors he saw no threat the freedom of the press in the jailing for contempt of court of a New York Times reporter for refusing to turn over his notes to defense attorneys in a murder case or a recent Supreme Court decision allowing police to search the offices of the Stanford University Daily.

He said the issues in both cases could be resolved "quite readily" by legislation, administrative action or further court decisions, and added, "I really don't feel as president . . . that there is a trend in our country away from protecting the right of freedom of speech or freedom of reporting the news."