President Reagan, in a preelection pep talk to Republicans, delivered a battle cry for his party last night, ridiculing Democratic Sen. Donald W. Riegle Jr. as the "demagogue from Michigan" and branding Gov. Edmund G. (Jerry) Brown Jr. as "California's Mr. Medfly."

Speaking by satellite television broadcast to 11 Republican fund-raisers across the country, the president declared that he remains "upbeat" about the Nov. 2 election outlook despite predictions by others that GOP congressional losses will exceed the traditional amount in a mid-term election.

"I know in the first off-year election there is a great loss" of congressional seats, he said. "I don't think there is going to be as great a loss as is traditional."

Reagan offered Republican congressional candidates at the fund-raisers a full platter of "good news" they can campaign on in the final days before the election, such as a drop in the inflation and interest rates, a slowdown in the rise in government spending and lower taxes.

Shedding the presidential mantle of nonpartisanship that he claimed to don for his economic speech Wednesday night, Reagan asserted that Republicans are fielding "good candidates," have an edge in fund-raising and, "in spite of what you hear on the news, I believe the issues are on our side."

"The economic issue that the opposition is trying to bully us with is like the bully himself," the president said in his opening remarks. "Once you stand up to him, he slinks away."

Reagan then proceeded to deliver a few punches of his own. He pointed out to Republicans that he was being "beamed" by satellite from Washington to various points across the country, and joked that "the way I am beaming all over the place, I'm afraid someone is going to mistake me for Jerry Brown."

Democrat Brown is in a tight Senate race against San Diego Mayor Pete Wilson, the Republican nominee. The campaign is high on the White House political agenda.

"I heard that diatribe that followed my broadcast" Wednesday night, Reagan said of the Democratic response, which was delivered by Riegle. Reagan called the senator a "demagogue," and offered a dictionary definition of the word as someone who plays on emotions to their own benefit.

The president bristled at Riegle's suggestion that Reagan was responsible for the current 10.1 percent unemployment rate; Reagan noted that the jobless rate had increased only 2.7 percent since he took office.

The president took one question by telephone from each GOP function.

Asked by a Michigan candidate what to tell voters in that economically depressed state, Reagan said: "I wish I could say there was something we could do instantly" about the jobless rate. The message for voters, he said, is that "the unemployment started long before our economic recovery program."

The Republican National Committee screened the questions; all were carefully phrased to give the president an opportunity to showcase his campaign message.

The purpose was to motivate Republicans in the final 19 days of the fall congressional campaigns and to put a bright edge on the increasingly gloomy economic news.

Reagan also took a few shots at Capitol Hill. "We haven't really been given a fair chance at showing what we can do," he said of the Congress, which delivered most of what he sought in his original economic program. He expressed his desire for a Republican majority in both houses of the next Congress, saying "that's what we would like to have."

In fact, Republican strategists have no hope of capturing the House from the Democrats, and have made it their top priority to maintain GOP control over the Senate.

While Reagan was seeking to boost GOP candidates last night, he stumbled on a question from New Hampshire. Each questioner was introduced to him by White House political director Ed Rollins. In this case, however, the woman who asked the question, Lois Beaulieu, was not the candidate. Nonetheless, Reagan unwittingly gave her his warm endorsement. The Republican nominee in the race against Rep. Norman D'Amours (D-N.H.) is Robert C. Smith.

Reagan expressed frustration at the pace of budget-cutting this year in Congress. He blamed the "big spenders" and the House Democratic leadership, which he claimed have "never helped us" although "I have to be honest and say I have had the support" of some Democrats.

"I wish it were possible all at once to make a slash in spending," he said. "You can't do it all at once. You would be pulling the rug out from people" who depend on social programs. "We are going to preserve the safety net for those who most depend on the rest of us," he added.

The White House has been getting numerous last-minute requests for Reagan to make campaign appearances around the country, but his aides are planning only a few days of campaigning for him beyond a two-day foray to Illinois and Nebraska next week.

His comments last night were an effort to help those candidates for whom he cannot campaign in person. Reagan delivered his remarks at the U.S. Chamber of Commerce building across Lafayette Park from the White House, and they were transmitted to GOP dinners in Sacramento; Denver; Bloomington and South Bend, Ind.; Wichita, Kan.; Lansing, Mich.; Manchester, N.H.; Mansfield, Ohio; Tullahoma, Tenn.; Longview, Tex., and Bellingham, Wash.

On Monday Reagan is to make another such broadcast to 20 locations.

White House deputy press secretary Larry Speakes said that, to avoid duplication in the questions, the Republican National Committee reviewed them in advance. Speakes said the questions were not shown to the president.