Donald Trump pivoted to his re-election bid on Thursday night as House Democrats held the Senate floor arguing for his conviction and removal.

House Intelligence Committee Chairman Adam Schiff played videos of current and former Trump administration officials' testimony implicating the president in a pressure campaign aimed at convincing Ukrainian officials to investigate his top Democratic rivals. He said bluntly that "Donald Trump put himself first" and over the interests of the United States.

The California Democrat the president mocks with the "Shifty" nickname called the investigations Trump and his aides wanted Ukraine to launch were "improper" and "inappropriate" and "wrong.

But as Mr Schiff was saying those desired "investigations were not about anything but Donald Trump's political gain," the president was onboard Air Force One focused on the leading Democratic presidential candidates.

There is no evidence that the seven House Democratic impeachment managers have convinced 20 Senate Republicans to vote with the minority party to convict and remove Mr Trump.

As he flew to one of his Florida golf resorts for a Republican Party event, Trump was in full campaigner in chief mode.

Taking aim at two of the leading Democratic frontrunners - Vermont senator Bernie Sanders and former Vice President Joe Biden - the president sought to discredit both candidates.

"Crazy Bernie takes the lead in the Democrat Primaries, but it is looking more and more like the Dems will never allow him to win!" he wrote, keeping alive his contention that former Secretary of State Hillary Clinton and those aligned with her blocked Sanders from capturing the party's nomination in 2016.

Though he recently expressed public surprise at Sanders' recent surge in polling in early voting states like Iowa, the president long has said he thinks Mr Biden will be his general election foe. So he got in a dig on the former Delaware senator, too.

"Will Sleepy Joe be able to stumble across the finish line?" the 73-year-old Mr Trump said, using another derisive nickname to suggest the 77-year-old Mr Biden is too old to be the 46th commander in chief.

Despite the president's bravado, recent polls suggest the Senate impeachment trial might be influencing his re-election race.

For instance, a CNN poll released Wednesday put Mr Biden ahead of him by 9 percentage points in a hypothetical national one-on-one race. The same survey gave Sanders a 7-point national lead.

Those are wider margins than another poll released nine days earlier. That IBD/TIPP survey showed Mr Trump trailing Mr Biden by 2 points and Sanders by a single point; both are within that poll's margin of error.