The first joint appearance of Barack Obama and Hillary Clinton is due to happen on Friday, in the small New Hampshire town of Unity.
The former rivals plan to campaign together in order to ease tensions over the closely fought Democratic primary.
The announce of the location was made on Monday. The small town was not only chosen for the symbolism of its name, but because in the January 8 primary, that Ms Clinton won, each candidate received exactly 107 votes.
Besides, New Hampshire is a critical battleground state in the November election. In his unsuccessful 2000 presidential bid, John McCain, the Republican candidate, won the state’s primary, and prevailed again this year.
Ceding the spotlight to the two foes, former president Bill Clinton does not plan to appear with his wife and Obama.
The day before the rally, Barack Obama and Hillary Clinton will meet privately at a Washington hotel, with former Clinton donors. The former first lady will introduce Mr Obama to her financial backers, who have been slow to embrace her one-time opponent.
Earlier this month, the New York senator suspended her campaign for the Democratic nomination after the Illinois senator secured enough delegates to clinch the nomination. “I endorse him and throw my full support behind him”, she said at the time.
Mo Elleithee, Ms Clinton spokesman, said the former Democratic candidate will make the same pitch to her supporters, telling them that they should support Mr Obama “with everything we still need to accomplish and with the stakes as high as they are”.
The two former rivals spoke by phone Sunday night, and though Barack Obama spokesman, Robert Gibbs confirmed the telephone conversation, he refused to give details.