Washington  - Presumptive Democratic presidential nominee Barack Obama and former rival Hillary Clinton will hold their first post-primary rally Friday in the small town of Unity, New Hampshire.

The site, chosen for its obvious symbolism to bring the centre-left party together, will see the start of the defeated Clinton's work to help Obama for the November general election against John McCain, the presumptive nominee of the centre-right Republican Party.

Friday's rally follows their first joint appearance since the final intra-party contests more than three weeks ago. Obama and Clinton appeared together in Washington at an event with the former first lady's top campaign donors.

At the same time, Obama, a US senator from Illinois, wrote a personal cheque for 2,300 dollars - the maximum individual contribution - to Clinton's own presidential campaign. The New York senator has suspended her campaign but remains 20 million dollars in debt, and she has sought Obama's help in raising money to pay off the unpaid tab. (dpa)