As he testifies Tuesday before the Senate Judiciary Committee, former acting FBI director Andrew McCabe will forcefully defend the bureau’s decision to initiate an investigation into whether the Trump campaign coordinated with Russia to influence the 2016 election, telling lawmakers that officials had a “duty” to do so because of the information that had come to them, according to a copy of his prepared remarks.

McCabe, a longtime FBI official who briefly led the bureau after President Trump fired Director James B. Comey in 2017, is the fourth former high-ranking law enforcement official to testify before the Republican-controlled committee as a part of its review of the Russia investigation.

Like those before him, McCabe will concede some mistakes — particularly in how the bureau applied to a secret court to conduct surveillance on a former Trump campaign adviser — but offer a robust counter to broader conservative attacks on the investigation, according to a copy of his prepared remarks. McCabe personally approved the decision to investigate Trump for possible obstruction of justice and is likely to face questions on that decision.

“Let me be very clear. We didn’t open a case because we liked one candidate or didn’t like the other one. We didn’t open a case because we intended to stage a coup or overthrow the government. We didn’t open a case because we thought it might be interesting or because we wanted to drag the FBI into a heated political contest,” McCabe will say, according to the remarks. “We opened a case to find out how the Russians might be undermining our elections. We opened a case because it was our obligation — our duty — to do so. We did our job.”

The probe by the committee’s chairman, Sen. Lindsey O. Graham (R-S.C.), is one of several efforts to investigate the investigators who led the Russia probe. If Republicans maintain control of the Senate, it is perhaps the one most likely to persist after President-elect Joe Biden is sworn in.

The investigation is largely seeking to build on that of Justice Department Inspector General Michael Horowitz, who found the FBI had adequate reason to initiate the probe but made serious, troubling errors in applying to the Foreign Intelligence Surveillance Court to monitor former Trump campaign adviser Carter Page. It comes in addition to the investigation by U.S. Attorney John Durham, who was specially tapped by Attorney General William P. Barr to review the Russia probe and has publicly signaled some disagreement with Horowitz.

Democrats allege all the efforts are politically motivated attempts to undercut an investigation that dogged Trump’s campaign. It is unclear how the Justice Department in Biden’s administration might handle the Durham probe, or if it could perhaps finish before Trump leaves office.

The committee already has heard testimony from former deputy attorneys general Rod J. Rosenstein and Sally Yates, as well as Comey. Each defended opening the investigation while conceding mistakes in the applications on Page, which they signed off on.

McCabe, according to the remarks, will outline how the bureau had been tracking Russian cyber actors since 2014, but became severely alarmed in 2016, when Russian intelligence agents dumped online hundreds of thousands of emails they had stolen from the Democratic National Committee.

When agents later learned that a foreign policy adviser to the Trump campaign had boasted to a foreign diplomat that the Trump campaign had “received indications from the Russian government that it could assist the Campaign through the anonymous release of information that would be damaging to Hillary Clinton,” they had no choice but to explore possible Russia-Trump coordination, McCabe will say, according to the remarks.

McCabe will also warn that — despite fairly limited evidence of foreign interference in the 2020 election — American officials should stand on guard for future attacks.

“Simply put, the Russians, and others, will be back,” McCabe will say, according to his prepared remarks. “Do not let the recent calm of the 2020 election lure the nation into a false sense of security. It is up to you to ensure the nation recognizes the magnitude of the threat posed by foreign actors and takes sufficiently aggressive steps to address it.”