WASHINGTON — Two Republican senators have said they are continuing to look into "potential conflicts of interest" with Hunter Biden's business dealings in Ukraine and China, shortly after President Donald Trump was acquitted by the Senate on articles of impeachment for his own conduct in Ukraine.

Sens. Chuck Grassley, R-Iowa, and Ron Johnson, R-Wis., sent a letter to Secret Service Director James Murray on Wednesday asking for clarification on "whether Hunter Biden used government-sponsored travel to help conduct private business" and details of his travel records.

In defending Trump from accusations that he improperly pressured Ukraine to open investigations into former Vice President Joe Biden and his son, Republicans have sought to shift the focus onto their claim that Biden conducted foreign policy in order to benefit his son's business interests in Ukraine, for which there is no evidence.

Analysis:Tougher than Teflon? Trump shows he is the most resilient politician in modern US history

They claim the reason Joe Biden pushed out a former Ukrainian prosecutor was to quell a probe into the Ukrainian energy company for which Hunter Biden served on the board. The former vice president's position was actually that the prosecutor wasn't tough enough on corruption cases in the nation, a view shared by international leaders and anti-corruption groups.

Democrats have said Trump only wanted investigations to damage Joe Biden in the 2020 election and allegations of corruption against him had been debunked, while Trump's legal team argued in the Senate trial that the president had legitimate reasons to be concerned.

Fact check: What really happened when Biden, allies pushed out Ukrainian prosecutor

Johnson was a figure in the impeachment saga because he attended the inauguration of Ukraine's president last year and confronted Trump when he heard that aid to Ukraine may have been linked to investigations of Trump's rivals.

Grassley and Johnson, who respectively chair the Senate Committee on Finance and Committee on Homeland Security and Governmental Affairs, have previously requested records related to Hunter Biden from the State and Treasury Departments. They both voted that Trump was not guilty in the trial.

In their Secret Service letter, the GOP senators asked for a description of the protective detail Hunter Biden received during his father's time in office and a list of his travel dates and locations, along with other information, for which he received a detail.

Johnson's role:Wisconsin Senator gives Republicans an account of his involvement with Trump, Ukraine

Senate Judiciary Chairman Lindsey Graham, R-S.C., has also said he intends to pursue the Bidens.

"The day of reckoning is coming for congressional and Senate oversight of Joe Biden," Graham told Fox News on Sunday, before the acquittal vote. Graham said he hopes the Senate Foreign Relations Committee will call witnesses, including Hunter Biden, to testify about the matter "in the coming weeks."

"They ruined America's ability to effectively deal with corruption in the Ukraine by having Hunter Biden on the board of Burisma. That's just a fact," Graham said. "And we're going to get to the bottom of it.

The former vice president, for his part, has dismissed all allegations as conspiracy theories, but acknowledged Hunter Biden's role created a "bad image."

"No one's found anything wrong with his dealings with Ukraine except they say it sets a bad image," Joe Biden said on Monday.

'He's changed':Jill Biden says 'it's hard' to consider Lindsey Graham a friend amid Ukraine controversy

Contributing: William Cummings