Sen. Ted Cruz (R-Texas) said it is "maddening" that the federal government had communications from home-grown terrorists before they attacked but refused to act.
Cruz said the federal government was aware of threats but did nothing before the 2009 Fort Hood terror attack.
Cruz charged the Obama administration with "willful blindness," and said it caused the nation to be "handcuffed by political correctness."
The former Republican presidential candidate said he commends the Trump administration for taking seriously the threat of terrorists slipping through a weak immigrant vetting process.
Cruz' comments come in the wake of two horrific terrorist attacks in Britain - in Manchester and on London Bridge.
Cruz said that preventing terrorist attacks should not be a partisan issue, and politicians should not be squabbling over it.
"They're mad at the American people for electing a Republican president" and giving the Republicans majorities in the House and the Senate, Cruz said of the left.
The senator previously introduced legislation for a three year moratorium on refugees from nations where radical Islam controls large portions of territory.