President Barack Obama will Friday mark the second anniversary of his declaration of the end of US combat missions in Iraq, highlighting his leadership credentials at a key political moment.

Obama will fly to Fort Bliss in Texas to meet service members and their families, one day after the end of the Republican National Convention and days before he headlines the Democratic Party's jamboree in North Carolina.

He last traveled to the sprawling base on the Texas and New Mexico border two years ago, to meet troops home from the war, hours before delivering a televised address on the end of combat operations from the Oval Office.

"The visit will focus on, I think, that important anniversary," said White House spokesman Jay Carney.

"It will also focus on the fact that the president has always said that part of ending the war in Iraq responsibly is standing by those who served."

"The president will focus his visit on our efforts to support US service members and their families as we have ended the war in Iraq and are winding down the war in Afghanistan."

Obama declared the end of American combat operations in Iraq, after a seven-year war, on August 31, 2010. All US forces returned home at the end of last year.

Although Obama's trip is billed as an official one, consistent with his duties as US commander-in-chief, it will be seen in a highly political context.

The president made his political name opposing the Iraq war even before he was elected to the Senate in 2004, and regards bringing US troops home as the fulfillment of one of his core political promises.

His decision will feature prominently next week in three days of speeches and events culminating in his acceptance of the Democratic Party nomination as he seeks a second term in the White House in November.

Polls show that Obama's foreign policy performance is one of his strongest credentials as he asks voters for re-election, even as Republicans accuse him of weakness abroad and of presiding over an erosion of US power.