After the House's parliamentarians raised concerns, both men were sworn in Thursday afternoon by Boehner.
Six votes cast by Fitzpatrick and Sessions had to be stricken, the same congressional official said. On Friday, the official said, the House may take further steps to ensure that the election of members to committees and other procedures were done properly.
The Associated Press reported that House Republican leaders planned to correct the foul-up with a resolution asking that the two men's votes be nullified, but that the voting results stand.
That is part of the same resolution that sets rules for debating the GOP's centerpiece bill next week: repeal of the health-care law.
Democrats seized on the misstep, trumpeting that on the same day the Republican-led House read the Constitution on the House floor, two GOP members had to be sworn in again to become legal. The Pennsylvania Democratic Party lambasted Fitzpatrick for "glad-handing" instead of being on the floor Wednesday.
In a separate news release, the Democrats' congressional campaign unit said, "Republicans have spent a lot of time over the past two days proselytizing about House rules, but they don't seem very keen on actually following the rules."
Smith, the aide to Fitzpatrick, denied Democrats' claim that Wednesday's gathering in the visitors center was a campaign fund-raiser.
More than 500 supporters went to Washington for Fitzpatrick's swearing-in, many paying $30 to ride six buses from Doylestown and Langhorne. About 200 in the group drove down separately, he said. Lunch was paid for with campaign money, he said.
Even so, an online sign-up sheet for the excursion solicited contributions of $30, $60, $90, $120, or "other," and identified the sponsor as the
"Fitzpatrick for Congress" campaign committee. The form also said participants could "donate by check."
Smith said the various amounts listed on the form were because "some people reserved multiple seats. The purpose of the charge was to pay for the buses, period."
Fitzpatrick didn't intend to be off the floor, Smith said. The swearing-in had been expected to take place closer to 2:45 p.m., but happened about 2:15 p.m.
Fitzpatrick, who served a term in the House before losing his seat in 2006, did not think there was a problem with swearing the oath in the visitors center, Smith said, but the congressional parliamentarian he consulted was "a little more concerned about it."
Fitzpatrick did not immediately respond to calls for further comment.
Contact staff writer Joelle Farrell at 610-313-8207 or firstname.lastname@example.org.