Vice President Mondale and Sen. Edward M. Kennedy today rekindled an argument that began last month in Iowa over Presidents Carter's foreign policies and Kennedy's right to criticize them.

Told at the final stop of his tour here that Kennedy had complained Mondale was impugning his patriotism and contributing to a war hysteria, the vice president replied, "That's bunk . . . I have never attacked Sen. Kennedy's patriotism -- and he knows it."

The vice president has told Maine Democrats the last two days that the "world will be watching" Sunday to see if they support a president with "backbone," or challengers who offer nothing but "election-year gimmickry . . . hocus pocus and hokum."

That the University of Maine today, Kennedy, waving a newspaper quoting Mondale, asked "If he [Carter] has so much backbone, why won't he come up here to the state of Maine and start debating the new Carter doctrine that may very well register you [ for the draft] and send you to the Persian Gulf . . . Where is the backbone of the president of the United States in facing up to the oil companies?"

Alluding to criticism he has received for attacking Carter's policies, Kennedy said, "You raise your voice in the Congress . . . and they'll whip out old Fritz Mondale and question your patriotism. That's the kind of campaign they're running."

The dispute between the two men who were close friends and allies in many liberal causes during Mondale's Senate days came as Mondale worked his way south from Bangor to Kittery, just across from here, seeking a big turnout in the Maine town caucuses Sunday which mark the second step on the 1980 Democratic delegate selection trail.

As he began yesterday at a reception in the Bangor home of Hannibal Hamlin, Lincoln's first vice president, Mondale implied that his unusually melodramatic rhetoric was occasioned by the belief that the race between Carter and Kennedy "is just as tight as it can possibly be."

But as reporters heard local Democratic officials at stop after stop say Carter was far ahead of Kennedy in their area, Mondale abandoned that pretense and in effect confirmed that the goal is to beat Kennedy badly enough in Maine to cripple the Masschusetts senator's chances of a last-ditch revival in the Feb. 26 primary in New Hampshire.

By this after, as he left the state, Mondale acknowledged that canvassing shows "Maine voters are overwhelmingly for President Carter" and that only complacency by stay-at-home Carter supporters could deny the incumbent a victory to match his Iowa triumph.

The extent to which the Carter forces are prepared to go to ensure a victory was indicated by the decision to call Kenneth M. Curtis, the state's popular former governor, back from his duties as ambassador to Canada last Thursday for a week of campaigning on behalf of the president. Mondale, who has argued that the gravity of the world situation keeps Carter from campaigning, said it was "perfectly proper" for Curtis to take the unusual action for an ambassador of engaging in a partisan political campaign. "He's entitled to do that," Mondale said, "and I'm proud of his support."

Curtis, who joined Mondale for part of today's schedule, said his solo stumping in northern Maine found Carter far ahead of Kennedy in the isolated, rural communities. The apportionment of delegates favors those communities against the major population centers like Portland and SacoBiddeford, where Kennedy is believed to have more strength.

Because of uncertainty of the turnout and the possibility that Kennedy and California Gov. Edmund G. (Jerry) Brown Jr. may recruit numbers of new participants from the college campuses, Mondale drew the line on Carter's challengers with unusual acerbity for one who is normally polite in his campaigning.

Saying Maine voters know "there is no substitute for character" and that "if a person doesn't have backbone, not even a surgeon can give him one," Mondale said Carter's reaction to the crisis in Iran and Afghanistan demonstrated his fundamental difference from his rivals.

The vice president depicted Carter's decision to embargo grain sales to Russia, to have U.S. athletes boycott the Moscow Olympics and to seek registration of youths for possible military service as acts of courage by a president unconcerned about the personal political risks involved.

By contrast, he said, Carter's opponents criticized all those stands, thinking that public opinion would not support the president's actions. "They were swarming around us like bees," Mondale said of the Carter challengers. "But the American people rallied behind the president," who, in Mondale's words, "is working around the clock to teach the Soviets a lesson before it's too late to save the peace."