The Democrats and the Republicans are not the only political parties in the United States. But the overwhelming majority of Americans identify and cast ballots for them. In this segment of "How America Elects," VOA's Jeffrey Young explains how the Democrats and Republicans have evolved over time, and their differing positions on major issues.

Politics is a marketplace of ideas and the groups that promote them. Among the most prominent of these groups are the Democratic and Republican Parties.

The Democrats and the Republicans have controlled the White House and Congress for one and a half centuries. But the two parties have always been adversaries, aggressively competing for America's middle-ground voters.

"Historically, the Republican Party has stood for a smaller federal government, for lower taxes, for less federal spending, probably [as well] having problems solved at the state and local level, or just in the private sector," says Frank Donatelli, Deputy Chairman of the Republican National Committee. "Internationally, the party favors a strong national defense, an America acting in its own self-interest, but obviously, in conjunction with its allies."

The rival Democratic Party has a different philosophy.

"Ideologically, the Democratic Party is liberal, left-of-center, in the United States," according to Michael McDonald, who is at the Washington independent research group The Brookings Institution. "And generally, they [the Democrats] are for larger government, [a] larger role of government in regulating society, providing benefits and services to people within the society, mainly of lower class.

The Democratic Party took that stance some 75 years ago, when Franklin Delano Roosevelt became president at the height of the Great Depression. FDR launched a massive program called the "New Deal" with economic and social reforms meant to uplift average Americans.

FDR's Democratic coalition of large cities, blue-collar voters, and the southern states held until the 1960s, when the Republicans began to attract working class whites, especially in the south. Michael McDonald describes today's Democratic Party:
"So there is a coalition there of persons of color. And then you also have people who are more highly educated, people who are also somewhat higher income as well who form kind of a liberal elite, if you will, within the society. And also, women."

Along with big cities, the Democrats are strong in the industrial northeast, the Pacific coastal states, and with younger people.

For the Republican Party, [the late President Ronald Reagan, who held office from 1981 to 1989, has become an iconic figure like FDR.

Another Reagan legacy for the Republicans is the prominent inclusion of social conservatives such as fundamentalist Christians and anti-abortion activists.

The struggle for power between the Democrats and the Republicans goes beyond control of the White House. The Senate and the House of Representatives will also be a focal point on Election Day, 2008. Control of Congress will be essential to whoever wins the presidency if they want their agendas enacted.