Democratic presidential front-runner Hillary Clinton has largely steered clear of traditional radio and television advertising, instead nurturing the Internet audience and drawing the largest number of online visitors.

Clinton, a senator from New York and former first lady, had the most visitors to her Web sites in August, almost 760,000, compared to her rivals, but she ran only about 2,200 radio and television spots so far this year, according to Nielsen data released on Monday.

Sen. Barack Obama of Illinois, who has consistently run second in national polls, was a close second in the number of Web page visitors with about 750,000 in August, but ran almost double the number of radio and television spots this year with 4,300.

The Democrat who ran the most television and radio spots was New Mexico Gov. Bill Richardson with about 6,000. He has mostly registered in the single digits in polls. He had 103,000 Web site visitors in August, Nielsen found.

With a wide open field among Democrats and Republicans ahead of the November 2008 election, candidates are already spending millions of dollars on advertising and the Internet to draw support before the nominating contests early next year.

Among Republicans, former Tennessee Sen. Fred Thompson, who officially joined the presidential race in September, had the most separate visitors to his Web site in August, with some 410,000, according to Nielsen.

His numbers likely increased even further after he announced his presidential bid with a Web video.

Former Massachusetts Gov. Mitt Romney trailed with 291,000. Nielsen found he led the pack in advertising, running nearly 11,000 spots this year as he tries to introduce himself nationally — almost 10 times the number of the rest of the Republicans combined.

He has led polls in key early voting states like New Hampshire and Iowa, but Romney has yet to catch on in national polls and former New York Mayor Rudy Giuliani may be gaining some ground in those early states.

“Romney’s people have decided it’s do or die,” said professor Christine Williams of Bentley College in Massachusetts, who studies online politics. “His candidacy is essentially over if he can’t make a good impression in those early states” like Iowa and New Hampshire.