Sen. Ron Johnson, R-Wis., is asking the Secret Service about a "potential lapse in security" regarding Vice President-elect Kamala Harris's visit to Democratic National Committee headquarters on Jan. 6, 2021, the date rioters breached the Capitol.

In a letter sent Wednesday to Secret Service Director James Murray, Johnson noted that according to the FBI, pipe bombs were planted at the DNC office and that of the Republican National Committee on the evening of Jan. 5, 2021, but that according to news reports the U.S. Capitol Police did not begin investigating the alleged DNC pipe bomb until the afternoon of Jan. 6, after Harris was already there.

SEN. TUBERVILLE BLASTS DEMOCRATS FOR NOT SUPPORTING RESOLUTION TO REOPEN CAPITOL: ‘SOMETHING THEY CAN CONTROL’

"Given that Secret Service reportedly swept the areas in and around the DNC headquarters prior to Harris’ arrival on January 6, 2021, it seems odd that agents did not immediately discover the pipe bomb that was reportedly located next to a park bench at that location," Johnson said in his letter.

Fox News Digital reached out to the Secret Service for comment, but they did not immediately respond.

Johnson recalled that the Capitol Police reportedly began their investigation at approximately 1:07 p.m. local time, with the Secret Service escorting someone believed to be Harris out of the DNC building seven minutes later. Harris had been there since 11:30 that morning, 15-16 hours after the bomb had allegedly been planted.

Kamala Harris speaks at summit at White House

Vice President Kamala Harris speaks at the Tribal Nations Summit in the South Court Auditorium on the White House campus, Tuesday, Nov. 16, 2021, in Washington.  (AP Photo/Patrick Semansky)

The Republican senator asked Murray to provide information regarding when the Secret Service did a sweep of the DNC building before Harris's visit and which areas they investigated.

CLICK HERE TO GET THE FOX NEWS APP

"Please explain why Secret Service did not discover the pipe bomb reportedly located ‘next to a park bench’ near the DNC headquarters during their sweep?" Johnson asked. He also questioned whether the Secret Service has conducted any internal investigation of how they may have missed it, and requested any pertinent records from any such review.

Johnson also asked whether this has been referred to the Department of Homeland Security.