WASHINGTON - President Donald Trump's top intelligence official will be grilled by U.S. lawmakers on Thursday over the administration's handling of a whistleblower report central to an impeachment inquiry into the president.The acting director of national intelligence, Joseph Maguire, will testify to the House of Representatives Intelligence Committee after refusing to share the complaint with Congress, despite a law requiring that it be sent to lawmakers after an inspector general's determination that it was urgent and credible.Maguire has been in his position for less than two months.While the formal impeachment inquiry announced on Tuesday by House Speaker Nancy Pelosi is led by Democrats, some of Trump's fellow Republicans joined them in calling on the administration to send the report to Congress. Members of the House and Senate intelligence committees were allowed to see the complaint on Wednesday."Republicans ought not to be rushing to circle the wagons to say there's no there there when there's obviously lots that's very troubling there," Senator Ben Sasse, a Republican member of the Senate Intelligence Committee, said after reading the document.The Senate passed a resolution calling for the report's release by unanimous voice vote on Tuesday. The House passed a similar measure by 421-0, with two Republicans voting "present," on Wednesday even after the administration backed down and agreed to let the Senate and House intelligence committee members view the classified report in secure rooms on Capitol Hill.The dispute over the report is the latest chapter in an ongoing power struggle, with the Trump administration resisting efforts by Democratic lawmakers investigating the president's business dealings and actions to obtain documents, records and testimony from the White House and senior officials.The whistleblower report is believed to include an account of a telephone call on July 25 between Trump and Ukrainian President Volodymyr Zelenskiy, in which Trump pressed Zelenskiy to investigate a political rival, former Democratic Vice President Joe Biden, in coordination with the U.S. attorney general and Trump's personal lawyer.There is no evidence that Biden, or his son Hunter Biden, who served on the board of a Ukrainian company, acted improperly.The call occurred after Trump had ordered a freeze of nearly $400 million in American aid to Ukraine, which the administration only later released.The Trump administration released the official account of the half-hour call on Wednesday, a day after Pelosi announced that the Democratic-led House was launching the official impeachment inquiry.COMMITTEE FOLLOW UPDemocratic Representative Adam Schiff, who will lead the hearing as chairman of the House Intelligence panel, said after reading the whistleblower report that it was well-written, and called the allegations "deeply disturbing" and "credible.""The complaint... certainly provides information for the committee to follow up," he said.Schiff has said the Justice Department misinterpreted the law in blocking Maguire from disclosing the complaint.Maguire may also face questions about a report in the Washington Post on Wednesday that he had threatened to resign over concerns that the White House might press him to withhold information from lawmakers. Maguire, the former director of the National Center for Counterterrorism, issued a statement denying that report.After the public hearing at 9 a.m. on Thursday, Maguire is due to appear before the Senate intelligence committee in a closed session at 11 a.m.Trump named Maguire, a retired Navy admiral, as the acting intelligence director early last month. Trump has yet to nominate a permanent candidate, who would have to be confirmed by the Senate.Trump and Zelenskiy appeared side by side in New York on the sidelines of the U.N. General Assembly on Wednesday and denied impropriety in their call. The Ukrainian president told reporters: "Nobody pushed me."And at a news conference closing out three days of meetings around the U.N. General Assembly, Trump accused Democrats of launching the impeachment inquiry for political gain, "because they can't beat us at the ballot."