Last year was a breakout year for the Internet in American politics, surpassing radio, and in some cases newspapers, as an important source of campaign news, a research firm says.

Fully 75 million Americans, or 37 percent of the adult population, used the Internet in 2004 to get political news and information, discuss candidates and debate issues in emails, or participate directly in the political process by volunteering or giving contributions to candidates, the Pew Internet and American Life Project said in a recent report. When considering only online Americans, the percentage using the Internet in politics jumped to 61 percent.

The percentage of consumers who went online last year for political news jumped to 29 percent of the general population from 18 percent in 2000. Among Internet users, the percentages grew to 52 percent from 33 percent, respectively.

The Internet in 2004 surpassed radio as a prime source of campaign news, with 28 percent of Internet users listing the web versus 17 percent citing radio. Among broadband users, 38 percent cited the Internet as a major source of political news, compared to 36 percent who chose newspapers.

In using the Internet more for politics, online Americans were positive in their view of the web. Among those who get political news online, 56 percent said the Internet had "raised the overall quality of public debate." Among all Internet users, 49 percent agreed with that statement.

In the presidential race, 53 percent of the people who said they got political news from the Internet voted for Republican George W. Bush versus 47 percent for Democratic challenger John Kerry.

As to the reason the Internet has become so popular a political news source, more than half of online Americans cited the convenience.

The Pew study is based on telephone interviews between Nov. 4 and Nov. 22 with 2,200 adults, aged 18 and older.