Three years after the Republicans met here to nominate Ronald Reagan for president, the Democratic National Committee today charged Reagan with having a record of "broken promises."

A summary of the 1980 GOP platform released here as the Democrats began three days of meetings shows that Reagan broke his pledges on jobs, trade, investment and balancing the federal budget, according to party Chairman Charles T. Manatt.

Claiming that three-fourths of the platform's specific pledges remain unfulfilled, Manatt said, "If political promises fell under the jurisdiction of the Federal Trade Commission, the Republican administration would be found guilty of consumer fraud."

The national committee has scheduled hour-long sessions on Thursday and Friday with five of the six declared candidates for the 1984 nomination. Sen. Gary Hart (D-Colo.), who had made the original request for the "in-depth" discussions with party leaders, decided to bow out to be in Washington for the Senate debate on a defense bill.

On Friday, the committee members also are scheduled to hear from the Rev. Jesse Jackson, the civil rights activist who is considering making a run for the Democratic nomination.

Manatt said that he had invited Jackson at the request of Mayor Richard G. Hatcher of Gary, Ind. He added that Jackson will report on his voter-registration drive among southern blacks as part of the 10 minutes allotted to Hatcher, a vice chairman of the party, for his own report.

The party chairman took the first step today to arm himself for a showdown with states that try to pick delegates earlier than party rules allow or by means the party does not sanction.

Manatt won executive committee approval to start creating machinery for the national party to conduct its own delegate-selection caucuses in states that violate its delegate-selection timetable or rules.

Several states are threatening to jump the gun or to use more lenient primary-election rules than the national party allows. The action taken today gives Manatt a club to wave over the heads of the recalcitrant states.

As the Democrats gathered, The Detroit News published a statewide poll showing that Sen. John Glenn (D-Ohio) would beat Reagan in Michigan by 50 to 41 percent, while former vice president Walter F. Mondale holds a narrow 47-to-45 percent lead over Reagan.

A National Journal survey of Democratic state party chairmen and other party leaders indicates that Glenn and Mondale are about even as the presidential choice of Democrats nationwide.

The latest Washington Post-ABC News poll showed Mondale leading Glenn by 33 to 27 percent among Democrats and independents. And a Harris Survey of Democrats and independents to be released Thursday shows them virtually tied, 48 percent for Mondale and 46 percent for Glenn.

The latest Iowa Poll shows Glenn gaining on Mondale in that state. Mondale is the choice for the nomination of 45 percent, with 30 percent for Glenn, 4 percent for Sen. Alan Cranston (D-Calif.), 3 percent for Hart and 1 percent for former governor Reubin Askew of Florida. In March, Mondale led Glenn by 55 to 17 percent, with 7 percent for Hart and 3 percent for Cranston.

The National Journal survey also indicates that party leaders see Glenn as gaining rapidly on Mondale, whose support they see as broad but shallow, and that there is no clear front-runner.

The party officials said that Mondale and Glenn are each leading in 11 states.

Those states where Mondale is said to be ahead are Alaska, Illinois, Iowa, Maine, Michigan, Minnesota, Montana, New Hampshire, North Dakota, South Dakota and Texas.

The ones in which Glenn is said to be leading are Arkansas, Florida, Idaho, Indiana, Kentucky, Mississippi, Nevada, Ohio, Tennessee, Utah and Virginia.