Montebello, Quebec ? President Bush offered a tepid endorsement of the Iraqi government on Tuesday, yet brushed off a Democratic senator’s call for the ouster of Iraqi Prime Minister Nouri al-Maliki.

Bush acknowledged his frustration with Iraqi leaders’ inability to bridge political divisions, but he said only the Iraqi people can decide whether to sideline the troubled prime minister.

“Clearly, the Iraqi government’s got to do more,” Bush said at the close of a two-day North American summit with the leaders of Mexico and Canada.

The Sept. 15 deadline for Bush’s next progress report to Congress is fast approaching, leaving the president little time to show that his U.S. troop buildup is succeeding in providing the enhanced security the Iraqi leaders need to forge a unified way forward.

In a speech today to the Veterans of Foreign Wars convention in Kansas City, Mo., Bush will argue that the troop buildup is helping bring former Sunni insurgents into the fight against al-Qaida and clearing terrorists out of heavily populated areas.

“Our troops are seeing this progress on the ground, and as they take the initiative from the enemy, they have a question: Will their elected leaders in Washington pull the rug out from under them just as they are gaining momentum and changing the dynamic on the ground in Iraq?” Bush says in his prepared remarks. The White House released excerpts of the speech Tuesday evening.

On Monday, Sen. Carl Levin, D-Mich., chairman of the Senate Armed Services Committee, said there is broad frustration with inaction from Iraq’s central government.

Levin, who recently returned from Iraq, urged the Iraqi Parliament to oust al-Maliki and replace his government with one that is less sectarian and more unifying.

And Sen. John Warner, R-Va., a former Armed Services Committee chairman and an influential voice on military affairs, joined with Levin in issuing a statement saying that while Bush’s military buildup in Iraq had “produced some credible and positive results,” the political outlook was dim.

In his VFW speech today, Bush will compare today’s war against extremists with the militarists of Japan and the communists in Korea and Vietnam.

In a speech to be given next Tuesday at the annual American Legion convention in Reno, Nev., the president will address the war in Iraq in the regional context of the Middle East.