A businessman who wants to take a stand against "sellout liberals" announced Friday he would challenge Sen. Hillary Rodham Clinton in the Democratic primary next fall.

Mark Greenstein, a 42-year-old self-described "new Democrat," has never held elective office but ran for president in 2000. He challenged Vice President Al Gore in New Hampshire's Democratic primary, winning 75 votes.

Greenstein acknowledged he had virtually no chance of defeating Clinton, who is popular in the state and has more than $17 million in the bank.

A former lawyer who now runs a chain of test-preparation centers, Greenstein said he would make national security, jobs, health care and clean government the key issues in his campaign.

He also said he would pledge to serve out his full six-year term if elected, and challenged Clinton to make the same commitment. Clinton is a potential 2008 presidential candidate.