The intelligence community inspector general (ICIG) on Monday appeared to push back on allegations that the rules regarding whistleblower reports had been changed shortly before the complaint regarding President TrumpDonald John TrumpAmash calls McCarthy incompetent, dishonest after '60 Minutes' interview GOP lawmaker blasts Trump for quoting pastor warning of civil war over impeachment '60 Minutes' correspondent presses McCarthy on impeachment inquiry MORE's dealings with Ukraine was filed. 

The Office of the Inspector General issued a four-page news release in which it made clear that the whistleblower complaint focused on Trump's July 25 call with the Ukrainian president was processed under procedures put in place in May 2018.

The inspector general wrote that under the statute, a complainant is not required to have firsthand knowledge of the matter they are referring. However, the anonymous author of the Aug. 12 complaint wrote that they had both firsthand information and information from others about the subject. 

"The ICIG reviewed the information provided as well as other information gathered and determined that the complaint was both urgent and that it appeared credible," the Office of the Inspector General said in Monday's news release. "From the moment the ICIG received the whistleblower’s filing, the ICIG has worked to effectuate Congress’s intent, and the whistleblower’s intent, within the rule of law. The ICIG will continue in those efforts on behalf of all whistleblowers in the Intelligence Community."

The clarification came as Trump and Sen. Lindsey GrahamLindsey Olin GrahamTrump allies go on the offensive against whistleblower complaint, Democrats Graham: 'I have zero problems with this phone call' Where's my Roy Cohn? MORE (R-S.C.) have claimed the rules for filing a complaint were changed just before the whistleblower on the Ukraine call came forward.

"This is a sham as far as I am concerned," Graham said on "Face the Nation" on Sunday. "I want to know who told the whistleblower about the phone call. I want to know why they changed the rules about whistleblowers not — the hearsay rule was changed just a short period of time before the complaint was filed."

Trump echoed the senator on Monday, asking in all caps "who changed the long standing whistleblower rules just before submittal of the fake whistleblower report?" 

WHO CHANGED THE LONG STANDING WHISTLEBLOWER RULES JUST BEFORE SUBMITTAL OF THE FAKE WHISTLEBLOWER REPORT? DRAIN THE SWAMP!

— Donald J. Trump (@realDonaldTrump) September 30, 2019

Sens. Chuck GrassleyCharles (Chuck) Ernest GrassleyIntelligence community strikes back — an impeachment game-changer Impeachment fight threatens trade deal Impeachment push threatens to derail bipartisan efforts on health care costs MORE (R-Iowa), Mike LeeMichael (Mike) Shumway LeeGOP opposition threatens to sink Trump's ATF pick Overnight Defense — Presented by Huntington Ingalls Industries — Furor over White House readout of Ukraine call | Dems seize on memo in impeachment push | Senate votes to end Trump emergency | Congress gets briefing on Iran Senate again votes to end Trump emergency declaration on border wall MORE (R-Utah) and Ron JohnsonRonald (Ron) Harold JohnsonRepublicans show signs of discomfort in defense of Trump   GOP battens down the hatches after release of Trump whistleblower complaint Impeachment fight threatens trade deal MORE (R-Wis.) wrote to Intelligence Community Inspector General Michael Atkinson on Monday asking for clarity about a reported change in the whistleblower complaint process that no longer required complainants to have firsthand knowledge.

Those senators wrote to Atkinson that they were not aware of any federal regulation that required whistleblowers to have firsthand knowledge, and they sought information on why such a policy might have been enacted.

The whistleblower complaint was made public last week. The individual's recounting of events matched up with a rough White House transcript of Trump's call with the Ukrainian president in which he urged the foreign leader to "look into" Democratic presidential candidate Joe BidenJoe BidenAmash calls McCarthy incompetent, dishonest after '60 Minutes' interview GOP lawmaker blasts Trump for quoting pastor warning of civil war over impeachment '60 Minutes' correspondent presses McCarthy on impeachment inquiry MORE.

The whistleblower further alleged that the White House sought to conceal the contents of the call and restrict access to the transcript to a small group of people.

The president has railed against the whistleblower, accusing the individual of being partisan and decrying their allegations as secondhand information. Trump has said he does not know the whistleblower's identity but told reporters earlier Monday that the White House was working on learning it.

The Whistleblower Protection Act makes it a violation for federal agencies to threaten retaliation against individuals who come forward to raise concerns of wrongdoing within the government.

Acting Director of National Intelligence Joseph Maguire last week called the complaint "credible" and said the whistleblower "did the right thing."