The Democratic-led House of Representatives has voted to send two formal charges against President Donald Trump to the Senate, clearing the way for only the third impeachment trial of a US president to begin in earnest next week.

Lawmakers voted 228 to 193 to give the Senate, controlled by Mr Trump's fellow Republicans, the task of putting him on trial on charges of abuse of power for asking Ukraine to investigate political rival Joe Biden and of obstruction of Congress for blocking testimony and documents sought by Democratic lawmakers.

The vote, which also approved a team of seven Democratic lawmakers named by House Speaker Nancy Pelosi to serve as prosecutors in the trial, was largely along party lines.

The 100-seat Senate is expected to acquit Mr Trump, keeping him in office, as none of its 53 Republicans has voiced support for removing him, a step that under the US Constitution would require a two-thirds majority.

But Mr Trump's impeachment by the House last month will remain as a stain on his record and the televised trial in the Senate could be uncomfortable for him as he seeks re-election next November. 

"We are here today to cross a very important threshold in American history," Ms Pelosi said on the House floor before the vote.

She launched the impeachment inquiry in September after earlier resisting such a move centered on Mr Trump's actions to impede a federal investigation that documented Russian interference in the 2016 election to boost his candidacy.

House Intelligence Committee Chairman Adam Schiff, a Trump nemesis who served as a federal prosecutor in Los Angeles for six years, was selected to head the team of House "managers." The White House has yet to unveil its defense team. The trial will overseen by US Chief Justice John Roberts.

Mr Trump, during a White House signing ceremony for a China trade deal, took a few shots at what he called the impeachment "hoax." He excused House lawmakers who needed to go to vote on impeachment and singled out for praise every Republican senator in the audience, whose support he will need at the trial.

White House spokeswoman Stephanie Grisham said Trump "expects to be fully exonerated," adding in a statement, "President Trump has done nothing wrong."

Opening statements in the trial are expected next Tuesday, according to Senate Majority Leader Mitch McConnell, whose fellow Republicans will set the rules for the trial.

A pivotal event in Mr Trump's impeachment was a 25 July telephone call in which he asked Ukraine's president to open a corruption investigation into Mr Biden and his son, as well as a discredited theory that Ukraine, not Russia, interfered in the 2016 US election.

Democrats have called this an abuse of power because Mr Trump asked a foreign government to interfere in a US election for his own benefit at the expense of American national security.

Mr Biden, the former US vice president, is vying for the Democratic nomination to face Mr Trump in the presidential election.

Republicans have argued that Trump's actions did not rise to the level of impeachable offenses. They have accused Democrats of using the Ukraine affair to try to nullify Mr Trump's 2016 election victory.

Democrats also accused Mr Trump of abusing his power by withholding $391 million in security aid to Ukraine as leverage to pressure Kiev into conducting investigations politically beneficial to him. The money - approved by Congress to help Ukraine combat Russia-backed separatists - eventually was provided to Ukraine in September after the controversy spilled into public view.

"The president considered that his private ATM machine, I guess," Ms Pelosi said of the aid on Wednesday.

Mr Schiff, 59, spearheaded the House impeachment investigation and he is a frequent target of Trump attacks. Mr Trump in December called Schiff "a deranged human being." 

The House managers also included Jerrold Nadler, who crafted the two articles of impeachment against Trump as House Judiciary Committee chairman, and Val Demings, a former police chief of Orlando, Florida.

Mr Schiff urged Republicans to allow more evidence and witnesses at the trial. Mr McConnell has resisted the idea of calling witnesses, saying senators should consider only the evidence amassed by the House.

Democrats want Mr Trump's former national security adviser John Bolton summoned as a witness. Other impeachment witnesses have said Mr Bolton was a vocal critic of the effort by Mr Trump's administration to pressure Ukraine.