July 27, 2016 9:54 PM EDT

President Obama is expected to declare Hillary Clinton as the deserving heir to the White House during his speech on the third night of the Democratic National Convention in Philadelphia.

The speech will mark the final stage of a remarkable relationship between the two from colleagues to rivals to friends.

The moment comes full circle for Obama, who shot to national fame 12 years ago with his “audacity of hope” speech at the 2004 Democratic convention. Four years later, it was Clinton who spoke in support of Obama as he advanced toward the presidency. The historic nature of his tenure and Clinton’s potential administration is not lost on Obama.

The two served in the Senate together, took jabs at each other during primary debates in 2008, joined forces as President and Secretary of State. Obama’s speech tonight will repay a favor, as Clinton spoke on his behalf at the 2008 convention.

Here’s a look back at their complicated relationship over the years.

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