BAGHDAD — US Vice President Joe Biden arrived in Baghdad on Saturday for a surprise visit aimed at bolstering Iraq's fledgling democracy almost four months after an inconclusive election.

Biden, wearing a blue blazer and khaki slacks, was accompanied on the trip by his wife Jill, who the White House said was on her first visit to the war-torn country.

The White House said that the couple was "in Iraq to celebrate the Fourth of July with US troops."

"During this visit, the Vice President will meet with Iraqi political leaders to reaffirm the US long-term commitment to Iraq and to discuss recent developments," said a White House statement.

Biden was greeted by US ambassador to Baghdad Christopher Hill, US commander in Iraq General Ray Odierno and Iraqi Foreign Minister Hoshyar Zebari upon his arrival at about 5:30 pm (1430 GMT).

Minutes after landing he also met and shook hands with John McCain, Joseph Lieberman and Lindsay Graham, US senators who landed Friday night on a separate visit to the Iraqi capital.

The three hawkish senators had earlier urged Iraqi leaders to act faster to form a coalition after meeting in Baghdad with the two main contenders for prime minister after the March 7 general election.

"We of course urge that there be a selection of a government that represents the results of the election and the will of the people," said McCain, the top Republican on the Senate Armed Services Committee.

"We are hopeful that the negotiations that are taking place between the respective parties will resolve in the formation of the government as soon as possible," the former presidential candidate told a news conference.

Lieberman, an independent, said the United States was keen to ensure its "ally" Iraq got a good government.

"Most important to us are two things: one is the government formed reflects all the people who voted in the election; and secondly that it be a nationalistic, independent government. Iraq for Iraqis," said Lieberman.

McCain said he and his colleagues had made no recommendation on the formation of the new government.

"We have not attempted to in any way recommend the specifics of the formation of the new government, but we obviously have urged that they move forward with as much speed and efficiency as possible," he said.

Biden visited Iraq in January when he came to try to defuse a political crisis after hundreds of candidates were barred from the March 7 poll over alleged links to now-executed dictator Saddam Hussein.

The United States has stepped up its diplomatic efforts in the past few weeks to help Iraq fill the prolonged power vacuum since the general election.

Last month, US Assistant Secretary of State for Near Eastern Affairs Jeffrey Feltman held talks with all of Iraq's main political leaders in a bid to promote an inclusive deal.

Washington is concerned about the stalemate since the March 7 election, as it is aiming to withdraw its combat troops and equipment from Iraq by the end of August.

On his visit, Biden will meet with Iraqi President Jalal Talabani, Prime Minister Nuri al-Maliki and his main rival for the premier's post, Iyad Allawi, according to the White House statement.

He will also meet with the UN envoy to Iraq, Ad Melkert, as well as take part in a July 4 event to mark US independence for Iraqi officials hosted by US ambassador Hill, it added.