The 2004 presidential campaign of Ralph Nader, political activist, author, lecturer and attorney began on February 23, 2004.

In April 2003, Salon reported that Ralph Nader was weighing whether to run for president in 2004, and that he was leaning towards doing so; he also met with several Green Party officials to discuss the possibility.

[3] Nader announced his intention to run for president during a February 22, 2004, appearance on the NBC's Meet the Press.

"[4] Candidates running in the Democratic primary were generally dismissive of Nader's announcement as well, with John Kerry announcing that he planned to "appeal to everybody in this race, and we'll make it unnecessary in the end for an alternative" and John Edwards responding that his goal was to unite voters across the ideological spectrum and that Nader "will not impact my campaign.

However, an effort was made by the Populist Party of Maryland to field candidates for governor, other statewide seats, and at the local level for the State Assembly, county, and municipal positions in the 2005 and 2006 elections.

[9] In Alabama and New York, a ballot line appeared in which running mate Peter Camejo was replaced with Jan D. Pierce, a Vice President of the Communications Workers of America and in 2000 was head of "Labor for Nader."

The caucus urged Nader to give up his presidential run, fearing that vote splitting would hurt John Kerry, the Democratic Party's nominee.

Representative Sheila Jackson Lee (D-TX) called the upcoming election "a life or death matter" for the Caucus members' constituents.

[20] Former president Jimmy Carter was also critical of Nader's 2004 candidacy; at a March 2004 Democratic fundraiser, Carter said "Ralph, go back to umpiring softball games or examining the rear end of automobiles, and don't risk costing the Democrats the White House this year as you did four years ago".

[21][22] Nader countered these criticisms by arguing that they were evidence that his detractors couldn’t fault him on policy-related grounds, and pointed to the estimated 45 million Americans who at the time lacked health insurance.