A bipartisan commission yesterday recommended that the two major political parties assume sponsorship of presidential campaign debates. The commission also called for a national voter registration day at least 30 days before each presidential election to promote a larger voter turnout and strengthen the political parties.

Reporting on its nine-month study of the presidential election process, the Commission on National Elections also proposed making the 1988 general election a national holiday, raising the limit on individual contributions to presidential candidates and simultaneous poll closings in all states.

It rejected the idea of regional primaries. But it urged that the initial primaries and caucuses, now dominated by Iowa and New Hampshire, be made more representative by encouraging states from other regions to hold theirs at the same time.

The commission concluded, however, that for the most part the election process "has served the nation well."

The study recommended at least three presidential candidate debates and said party sponsorship "would strengthen both the process and themselves."

At the presentation of the commission report, Democratic National Chairman Paul G. Kirk Jr. and Republican Chairman Frank J. Fahrenkopf Jr. signed an agreement endorsing party sponsorship of the debates while saying the nominees should make "the ultimate decision" about whether to debate.

The commission report said debates "deserve to be made a permanent part of the presidential election process" and party sponsorship is the best way to institutionalize them.

Dorothy S. Ridings, a commission member and president of the League of Women Voters, which has sponsored the candidate debates in the past, dissented.

She argued that party-sponsored debates "would probably never take place" because they "could be canceled at a moment's notice each time one candidate's demands were not met." She also said it "stretched the imagination to think that significant independent or third party candidates would ever be allowed to participate" in such debates.

Commission cochairman Melvin R. Laird, a former secretary of defense and Republican member of Congress from Wisconsin, countered that "the heat of the kitchen" would force the major parties to include "viable" third-party or independent candidates, such as John Anderson in 1980.

The commission was set up by the Georgetown University Center for Strategic and International Studies under the chairmanship of Laird and former Democratic National Chairman Robert S. Strauss. Members included Kirk, Fahrenkopf, Govs. Charles S. Robb (D) of Virginia and John H. Sununu (R) of New Hampshire, Sens. Lloyd Bentsen (D-Tex.) and John Heinz (R-Pa.), Katharine Graham, chairman of The Washington Post Co., Lawrence Grossman, president of NBC News, Roone Arledge, president of ABC News and Sports, AFL-CIO President Lane Kirkland, and elected officials and campaign managers from both parties.

The commission concluded that easier and increased voter registration is the key to Election Day turnout because studies show that 85 percent to 90 percent of registered voters go to the polls, compared with only about 53 percent of eligible voters in the 1984 presidential election.

"The inescapable conclusion is that this nation must do far more to enable every citizen to register to vote," the report said. "The most effective way to increase popular participation in national elections is to ensure that as many citizens as possible are registered."

The report noted that the commission was formed because of "widespread popular concern" about the presidential nominating and election process and the conviction of many of its members that there "are major flaws in the system" such as its length and cost and low voter turnout. It found, however, that after hearing testimony "from a broad range of thoughtful Americans . . . a somewhat different picture emerged" of a reasonably effective process, and it decided the "burden of proof rests on justifying proposals for change."

The report said the cost of presidential elections has gone down "in real terms" because of federal financing since 1972. "The problem of campaign finance has more to do with the amount of time and effort that presidential aspirants must spend in raising money," it concluded. The report urged faster disclosure of campaign contributions and stressed the need for better accounting of "soft money," contributions intended for local party building that often wind up as backdoor contributions to House and Senate candidates.

The commission said presidential campaigns are no longer than in the past, but because of the decline of parties some individual candidates have to "campaign longer and spend more money to become known.