BAGHDAD — Vice President Joseph R. Biden Jr. arrived in Baghdad on Monday to commemorate the official end of the United States combat mission and to meet with Iraqi political leaders, who have yet to form a government more than five months after elections. “We are going to be just fine; they are going to be just fine,” Mr. Biden told reporters as he prepared to confer with James F. Jeffrey, the new American ambassador in Baghdad, and Gen. Ray Odierno, the departing American commander in Baghdad. Lt. Gen. Lloyd J. Austin III, General Odierno’s successor, who will formally take command on Wednesday, and Gen. James N. Mattis, the head of Central Command, also attended the evening session with the vice president. The Iraqi public is increasingly discontented with the political gridlock, and American military leaders are concerned that a prolonged stalemate could lead to an erosion of security gains. In the past few months, insurgents have significantly increased the number of rocket and mortar attacks on the fortified Green Zone that houses the Iraqi government and on Baghdad’s international airport. An aide to Mr. Biden said Iraq had a functioning caretaker government and sought to dispel any sense of crisis. But he acknowledged that the delay in seating a new government had made it hard for Iraq to address longstanding political, legal and economic problems, and to further develop its relationship with the United States. “To build a partnership, you need a partner,” said Antony J. Blinken, Mr. Biden’s national security adviser. “The vice president is going to urge the leaders to bring this process to a conclusion.” The Obama administration has been reported to be sympathetic to a compromise plan in which Prime Minister Nuri Kamal al-Maliki might retain his post with somewhat more limited powers while a new council with binding authority would be established under Ayad Allawi.