CHICAGO (Reuters) - Presidential candidate Barack Obama will deliver a speech on Tuesday outlining his views of Iraq’s role in U.S. global strategic interests ahead of a planned trip there, his campaign said.

“He will focus on the global strategic interests of the United States, which includes ending our misguided effort in Iraq,” Obama spokesman Bill Burton said in a statement.

The presumptive Democratic nominee’s speech, which will take place in Washington, comes as his Republican rival in the November election, John McCain, has been accusing Obama of changing his position on Iraq.

Obama is expected to travel to Iraq and Afghanistan in the coming weeks but no dates have been disclosed for his trip because of security concerns.

Obama, who based his drive to capture the Democratic nomination on his early and ardent opposition to the war, said this month he might refine his plan to bring combat troops home within 16 months of taking office if conditions on the ground changed.

McCain, a Vietnam war hero and an Arizona senator, has attacked Obama, a first-time Illinois senator, as too inexperienced to serve as U.S. commander-in-chief.

In an opinion piece in the New York Times on Monday, Obama reiterated the 16-month timetable for pulling out U.S. combat troops.

“We can safely redeploy our combat brigades at a pace that would remove them in 16 months,” Obama said. “That would be the summer of 2010 — two years from now, and more than seven years after the war began.”

“In carrying out this strategy, we would inevitably need to make tactical adjustments,” the Democratic candidate said, adding that he would consult with U.S. commanders on the ground to make sure the withdrawal proceeds safely and that U.S. interests are protected.

Obama also welcomed Iraqi Prime Minister Nuri al-Maliki’s call to include a timetable for the withdrawal of U.S. troops in an agreement under discussion that would set the terms for the American military presence in Iraq.

(Reporting by Caren Bohan, editing by Philip Barbara)

(To read more about the U.S. political campaign, visit Reuters “Tales from the Trail: 2008″ online at http://blogs.reuters.com/trail08/)