The arrest of an Afghan national accused of planning an Election Day terror plot is fueling concerns from congressional lawmakers that there could be more potential terror threats who arrived as part of the tens of thousands who came to the U.S. in the wake of the withdrawal from Afghanistan.

"There was a vulnerability that was left that was able to be taken advantage of by, in this case, ISIS. It could be Taliban next time. It could be any other terrorist organization out there. And what I fear… is this is just one of probably tens, I wouldn't say hundreds, but tens of more individuals that are in the same situation," Sen. Markwayne Mullin, R-Okla., told Fox News.

Authorities announced last week the arrest of Nasir Ahmad Tawhedi, an Afghan national who came to the U.S. in 2021 after the withdrawal from Afghanistan. Tawhedi is charged with conspiring and attempting to provide material support to ISIS and receiving a firearm to be used to commit a felony or a federal crime of terrorism. Authorities say he liquidated his family's assets to finance his plan, including purchasing rifles and one-way tickets for his wife and child back to Afghanistan.

MAYORKAS REFUSES TO ANSWER QUESTIONS ON AFGHAN ACCUSED OF ELECTION DAY TERROR PLOT

"This defendant, motivated by ISIS, allegedly conspired to commit a violent attack, on Election Day, here on our homeland," said FBI Director Christopher Wray in a statement. 

Court filings initially stated that he came on a special immigrant visa but have since clarified that he came to the U.S. via humanitarian parole and later applied for SIV status.

A senior administration official told Fox News last week that Tawhedi was screened three times. He was screened first to work security for the CIA in Afghanistan, then for humanitarian parole to enter the U.S. in 2021, when he was vetted and screened in a third country, and then for special immigrant status, for which he was approved. His status has not yet been finalized. Officials believe he was radicalized after coming to the U.S.

AFGHAN NATIONAL CHARGED WITH ELECTION DAY TERROR PLOT REIGNITES VETTING CONCERNS 

There is also no indication that there were any red flags that should have barred his entry at any point in the process. His alleged co-conspirator in the case entered the country in 2018 and also passed vetting to receive a green card.

Tawhedi entered during the mass evacuation effort as the Taliban took back Afghanistan. The U.S. would go on to admit more than 97,000 evacuees, of which about 77,000 were admitted via humanitarian parole, through a program called Operation Allies Welcome. 

Republicans and the Homeland Security internal watchdog have repeatedly raised issues about the vetting process for Afghan nationals, and last week’s arrest has only served to refuel those concerns. 

"After the failed withdrawal from Afghanistan, we knew that there was no real vetting process of Afghan nationals coming into the United States. There were major concerns about potential terror plots to the homeland. This is the problem with the Harris-Biden administration," Rep Byron Donalds, R-Fla., said. "No accountability, no serious planning, covering up crises that, frankly, happen in front of the eyes of the American people."

AFGHAN MAN IN OKLAHOMA PLOTTED ELECTION DAY TERROR ATTACK IN US ON BEHALF OF ISIS, JUSTICE DEPT SAYS

The Biden administration has repeatedly defended the vetting process, arguing that there is a multilayered process that includes classified and unclassified vetting, including against Pentagon and FBI databases as well as Interpol notices and other information. 

"Afghan evacuees who sought to enter the United States were subject to multi layered screening and vetting against intelligence, law enforcement, and counterterrorism information," a DHS spokesperson said on Wednesday. "If new information emerges after arrival, appropriate action is taken." 

The two senators from Oklahoma have both received briefings from the FBI on the matter. Sen. James Lankford, R-Okla., also stressed the dangers facing the country.

"This is real. And we have people that are trying to be able to kill us that are within our own country, they're planning," Lankford told Fox News. "An open border is a danger. We've seen that already, that we're living on borrowed time through this moment."

Fox News’ Jacqui Heinrich contributed to this report.