WASHINGTON (CNN) -- Sen. Joe Biden, D-Delaware, will formally add his name to the growing list of 2008 presidential candidates on Wednesday, a Biden aide tells CNN.

Biden -- who first sought the Democratic nomination for president in 1988 -- will skip the initial step of forming an exploratory committee and make a formal declaration of candidacy instead.

Biden, who as chairman of the Senate Foreign Relations Committee has played a prominent role in the congressional debate over President Bush's call for a troop increase in Iraq, plans to make his first public appearance as a presidential candidate at the Democratic National Committee's winter meeting at the end of next week.

The Delaware Democrat will then begin a series of visits to early-voting states including Iowa and New Hampshire.

Biden will become the fifth Democrat to formally declare his candidacy for president. Former Iowa Gov. Tom Vilsack, Rep. Dennis Kucinich, Sen. Chris Dodd of Connecticut, and Former North Carolina Sen. John Edwards have all declared their candidacies.

Sen. Hillary Clinton of New York, Sen. Barack Obama of Illinois, and New Mexico Gov. Bill Richardson have established presidential exploratory committees but have yet to fully jump into the race.