"I join with all Americans in congratulating Iraq's new leaders and in wishing them well as they begin to serve their country in this new government," Bush said in a statement.
Iraq's interim National Assembly approved Cabinet members Thursday, ending nearly three months of political wrangling that had drawn increasing U.S. pressure. However, two deputy prime minister slots and five ministerial positions remain undecided and the list failed to meaningfully incorporate Iraq's Sunni Arab minority.
The handover to the new government — the country's first elected government since Saddam Hussein's ouster — was expected within days.
Bush spoke with Prime Minister-designate Ibrahim al-Jaafari on the telephone for about 15 minutes on Thursday to congratulate him and invite the Iraqi to visit Washington.
"I told him I was proud of the fact that he's willing to stand up and lead," Bush said at a White House news conference Thursday evening. "I told him I appreciate his courage and the courage of those who are willing to serve the Iraqi people in government."
Bush said he reassured al-Jaafari that the United States will continue to "stand by" Iraq. "I said, `I hope you get your constitution written on time' and he agreed," said Bush.
"He recognizes it's very important for the transitional national assembly to get the constitution written so it can be submitted to the people on time," Bush said.
U.S. officials had worried that the delay in getting a transitional government in place was hurting the effort to end Iraq's insurgency. Al-Jaafari had struggled to find consensus on his government's makeup since the Jan. 30 elections that put the parliament in place.
The next steps in Iraq's democratic transition include the writing of a constitution, its passage in a public referendum and an election for a new government by year's end.
Bush promised American help in all of those "important challenges," as well as in the fight against the insurgency and the training of Iraqi security forces to eventually take over from U.S. troops.
"The United States is confident that the new government will meet these challenges in the months ahead," he said. "America will stand by Iraq, its leaders, and the Iraqi people as they continue their work to establish a stable, peaceful, and democratic Iraq."
Secretary of State Condoleezza Rice, on a trip to Latin America, issued a statement congratulating the prime minister, his council and the Iraqi people. "For the first time in generations they have a democratically elected government," she said.