(Bloomberg) -- Democrats signaled their willingness to let some witnesses requested by Republicans testify as the House starts public impeachment hearings of Donald Trump this week, but only those people with knowledge of the president’s actions.

Ahead of the first session on Wednesday, Republicans gave the committee a list of witnesses they want called -- including Hunter Biden, former Vice President Joe Biden’s son, and the anonymous whistle-blower whose complaint sparked the inquiry.

Democratic Representatives Jackie Speier of California and Sean Patrick Maloney of New York, both members of the House Intelligence Committee, said on Sunday morning political shows that there are Republican witnesses panel Chairman Adam Schiff could call -- but not Biden’s son or the whistle-blower.

Speier suggested former National Security Council official Tim Morrison and former U.S. special representative to Ukraine Kurt Volker could appear. But Speier said the whistle-blower, whose identity is protected, isn’t needed, and any testimony has to be focused on the July call in which Trump pressured Ukrainian President Volodymyr Zelenskiy to investigate the Bidens.

‘Stay Focused’

“We want to stay focused on the Ukraine call,” Speier said on ABC’s “This Week” on Sunday, calling the conversation “a very strong case of bribery.” She added: “Having Hunter Biden come in is unrelated to the Ukraine call. And so that becomes irrelevant.”

Public testimony starting with career public servants could raise political risks for Trump as he seeks to de-legitimize the impeachment process while preserving his re-election prospects in 2020. But there is also risk for Democrats who are trying to build public support for impeachment and protect moderate members who will be campaigning in Trump-friendly districts next year.

Republican Senator Lindsay Graham of South Carolina, a vocal Trump ally, called the Democratic impeachment inquiry a “complete joke” because the whistle-blower has not been identified and subjected to cross-examination.

“If they don’t call the whistle-blower in the House, this thing is dead on arrival in the Senate,” Graham said on Fox News’s “Sunday Morning Futures.”

Representative Mac Thornberry of Texas, the top Republican on the House Armed Services Committee, said on ABC that what Trump did was “inappropriate” but not an impeachable offense. Fellow Texas Republican Will Hurd, a member of the House Intelligence Committee, said while Trump’s actions may have been illegal, impeachment may not be the right tool to address it.

“I think if you’re trying to get information on a political rival to use in a political campaign is not something a president or any official should be doing,” Hurd said on “Fox News Sunday.” “Most Republicans have said that would be a violation of the law.”

He said talk about impeachment “has been premature,” and said he wanted to see whether the actions established “a criminal intent.”

Republican Senator John Kennedy of Louisiana said on CBS’s “Face the Nation” the case could come down to Trump’s intent and motive -- and whether he was asking for an investigation of a political rival or a probe of possible corruption of someone who happened be a political rival.

Thornberry defended Republicans focusing on the process and complaints that Democrats are being too partisan, noting that under the U.S. legal system, murders, robbers and rapists are sometimes allowed to go free if their due process rights are violated.

“The integrity of the processes under our legal system is more important than the outcome of one particular case,” Thornberry said. “So I don’t think you can sweep under the rug.”

If a request for a probe of a rival could be proved, that would be “over the line,” Kennedy said. Asked whether that means impeachable, Kennedy replied, “yeah, probably” but that he wants to hear the testimony.

William Taylor, who took charge of U.S. embassy in Ukraine after the former ambassador was ousted in May, told House committees that he initially thought a July 25 phone call between Trump and the Ukrainian president “sounded like a good idea” as Ukraine sought to strengthen its fight against Russian-backed separatists.

But as the date approached, Taylor became concerned by the efforts of Trump’s personal lawyer Rudy Giuliani to involve Ukraine in an investigation of one of Trump’s political rivals, according to a transcript of the diplomat’s Oct. 22 closed-door testimony released Wednesday.

Taylor, a career diplomat, is scheduled to be one of the first two witnesses when the committee begins public hearings. He is scheduled to testify Wednesday along with State Department official George Kent. Former U.S. ambassador to Ukraine Marie Yovanovitch, who Taylor replaced, will testify two days later.

--With assistance from Christopher Condon.

To contact the reporters on this story: Mark Niquette in Columbus at mniquette@bloomberg.net;Craig Torres in Washington at ctorres3@bloomberg.net

To contact the editors responsible for this story: James Ludden at jludden@bloomberg.net, Steve Geimann

©2019 Bloomberg L.P.