WASHINGTON (AP) — A small group of House Republicans on Thursday urged President Donald Trump to declassify documents related to the beginning of the Justice Department’s Russia investigation.

Trump has already signaled he may do so, tweeting Thursday there may be “Declassification to find Additional Corruption.” He did not elaborate, but has repeatedly criticized the Russia investigation.

The Republican lawmakers, several of them staunch Trump allies, are asking the president take the unusual step of fully declassifying a secret wiretap application from 2016 for one-time Trump campaign aide Carter Page. The FBI was investigating Page’s ties to Russia, but Trump and his allies have insisted the wiretap was a way to spy on his campaign. The lawmakers also are asking Trump to declassify documents related to Justice Department official Bruce Ohr, who they say had inappropriate contacts with a former British spy who compiled a dossier on Trump’s ties to Russia.

The Republicans have spent much of the last year questioning the credibility of the Russia investigation that has hung over Trump’s White House, with a particular focus on the start of the investigation in 2016. Special counsel Robert Mueller took over the probe in May 2017.

They say the dossier, which was paid for by Democrats, was used inappropriately to obtain the warrant on Page and also start the Russia probe.