(CNN)A pair of Republican staffers on the House intelligence committee flew to London recently to try to find a way to bring the author of a dossier containing explosive allegations about President Donald Trump and top members of his campaign before the panel, sources familiar with the trip have told CNN.
Sources: House GOP staffers fly to London to find Steele, invite to testify expected
A congressional source familiar with the trip said House investigators are expected to send a letter to the author of the file, Christopher Steele, inviting him to testify before the House intelligence committee -- but it will have to be approved by the leaders of the panel's investigation first.
Steele, a former British intelligence official, has been a highly sought-after witness ever since it was revealed he wrote the dossier, which contained unverified claims that Russian operatives had compromising personal and financial information about Trump.
Trump always denied the claims, dismissing them as "phony" in January.
The trip by House Republican staff investigating Russian interference in the US election touched off a spat behind the scenes at the Capitol because Democrats on the investigation were kept in the dark, according to a separate source familiar with the trip.
But another source downplayed anger from Democrats on the House committee and Senate staff who were also seeking Steele, saying that it was not coordinated with them because the House Republican staffers' orders were to find a contact for Steele's lawyer -- not directly interview Steele in London or try to schedule an interview with Steele there.
"Are we not supposed to find witnesses?" the source asked.
The effort to bring in Steele speaks to the larger tug of war between House, Senate and federal investigators working with special counsel Robert Mueller, who are all competing for access to many of the same witnesses. The trip was first reported by Politico Friday.
Texas Rep. Michael Conaway, the leader of the House Russia investigation, was not immediately available for comment Friday. A spokesman for California Rep. Adam Schiff, the top Democrat on the panel, declined comment. And a spokesman for House intelligence Chairman Devin Nunes, also of California, who has largely stepped aside from the House Russia investigation but is still involved from the sidelines, did not return a request for comment Friday.
Last month, the Senate Judiciary Committee issued a subpoena for Glenn Simpson, the co-founder of Fusion GPS, the political firm that contracted Steele in compiling the dossier of unverified information for Trump's political opponents, prompting Simpson to agree to testify in private before the panel.