The turnout in the presidential election is expected to be one of the lowest this century, continuing a trend of declining voter participation in a nation that prides itself as a beacon of Western democracy, say political analysts.

Public interest groups are warning that only 50 percent or less of the eligible voters will go to the polls on Nov. 8, about the same as the record low 49 percent turnout in the 1924 presidential election.The declining turnout, down from a record high 79 percent in 1896, puts the United States at the bottom of the voter participation list in the world's democratic systems.

Belgium heads the average voter participation list with 95 percent, while the United States ranks last with 53 percent and Ireland second to last at 62 percent, according to figures compiled by Frances Fox Pi-ven and Richard Cloward in their book, "Why Americans Don't Vote."

The turnout in the last election, the 1984 contest between President Reagan and Democrat Walter F. Mondale, was 53.3 percent of the voting-age population. That was the lowest turnout since the 51.1 percent who gave Harry Truman an upset victory over Republican Thomas Dewey in 1948.

Most political scientists attribute the low American participation to the requirement that voters register days or weeks before they cast their ballot. In contrast, registration in West European democracies is generally automatic, with the voter receiving a notice in the mail.

"In fact, American registration procedures are Byzantine compared with those that prevail in other democracies," said Piven and Cloward.

Walter Dean Burnham, an expert on voter participation, says that without "the two-step hurdle" of registration and voting, turnout would increase 8 percent to 10 percent. Figures show that 87 percent of those who do register go to the polls on Election Day.

Other reasons cited by analysts for low participation include the declining power of the political party system, the generally apolitical nature of the electorate and television, which tends to focus on personalities rather than parties.

"As a result, people don't feel very represented and it's not very important for them to vote," said Burn-ham, a professor of government at the University of Texas at Austin.

Political parties in Europe are far more homogeneous than the Democratic or Republican parties in the United States, making it easier for voters to take sides and for the parties to target constituents, said G. Bingham Powell, chairman of the School of Government at the University of Rochester.

Many Americans do not identify with either of the two major parties, said Powell, who studies the difference between the U.S. and European political systems.