President Barack Obama was to hash out a strategy to counter the Islamic State group on Tuesday with military leaders from some 20 countries including Turkey and Saudi Arabia amid growing pressure on the U.S.-led coalition to do more to halt the militants' advance.

Some three weeks before U.S. congressional elections viewed largely as a referendum on Obama's leadership, the president was seeking to show the U.S. public and allies abroad that he is committed to a plan to "degrade" and "destroy" the group that has taken over large swaths of Iraq and Syria.

Obama will attend a meeting led by Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, with foreign defense chiefs at Andrews Air Force Base outside Washington at 3 p.m. to discuss the coalition's work.