The United States must resist the "urge" of isolationism under new leader Donald Trump and work with allies, outgoing President Barack Obama said Saturday ahead of his last visit to Europe.

Barack Obama on Monday harnessed history and all of his vaunted oratorical skill in a final campaign push to see Hillary Clinton elected the first woman president of the United States.

Obama spent the day campaigning for his first secretary of state, jetting from Michigan to New Hampshire to Pennsylvania.

How do you gift your popularity to someone else? As Barack Obama rolls up his sleeves to ensure Hillary Clinton succeeds him in the White House, his argument increasingly boils down to a simple message: Do it for me.

With approval ratings almost unheard of for an outgoing leader -- 54 percent, according to the latest Gallup average -- the Democratic president is hitting the trail full-time to help Clinton lock in crucial battleground states in the final stretch of the race.

The United States has tapped Jeffrey DeLaurentis, America's top diplomat in Havana, to become the first official ambassador to Cuba in five decades.

"The appointment of an ambassador is a commonsense step forward toward a more normal and productive relationship between our two countries," President Barack Obama said in a statement.

President Barack Obama is poised to veto legislation exposing Saudi Arabia to court action over the 9/11 attacks, stepping in to defend legal precedent and an awkward ally, but inviting election-time opprobrium.

White House officials say Obama will reject the "Justice Against Sponsors of Terrorism Act" by a Friday veto deadline, after a little over a week of deliberation.

U.S. President Barack Obama insisted diplomacy is the only way to end the brutal five-year conflict in Syria Tuesday, as a ceasefire brokered by Washington and Moscow lay in tatters.

"There's no ultimate military victory to be won, we're going to have to pursue the hard work of the diplomacy that aims to stop the violence and deliver aid to those in need," Obama told the United Nations.

U.S. President Barack Obama warned North Korea's government on Tuesday that provocative weapons tests would deepen the country's isolation.

U.S. President Barack Obama issued Sunday a disaster declaration for flood-devastated Louisiana, where emergency workers have rescued more than 7,000 residents stranded in homes and cars, said the White House.

The action makes emergency federal funding available to support rescue crews working nonstop as deadly flooding ravages the state, disastrous weather that has left at least three dead and one missing, said officials.

U.S. President Barack Obama warned Russia faces fierce international rebuke if it continues to make common cause with Syria's brutal regime, signaling a renewed push to end the bloody five-year civil war Thursday.

Obama said Russia risked casting itself as an "irresponsible actor" on the world stage, after meeting with top aides at the Pentagon.

President Barack Obama on Wednesday announced the deployment of 47 troops to crisis-ridden South Sudan to protect the US embassy and its staff.

"Although equipped for combat, these additional personnel are deployed for the purpose of protecting US citizens and property," Obama wrote in a letter to Congress released by the White House.