Rep. Paul Gosar (R-Ariz.) has planted himself in the limelight as Congress prepares to host Pope Francis this week. The question is: Since he says he’s not challenging Sen. John McCain (R-Ariz.) in 2016, why now?

The little-known Republican announced he will boycott Francis’s Thursday speech to lawmakers due to the pontiff’s views on climate change. Pope Francis has “adopted all of the socialist talking points, wrapped false science and ideology into ‘climate justice’ and is being presented to guilt people into leftist policies,” Gosar wrote in an op-ed piece at Townhall, a conservative news Web site.

The gambit is perhaps the most newsworthy thing Gosar — known in the past for staffing turmoil and a handful of health problems — has ever done. And so far, no other Republicans appear to be joining him in the boycott, even among the strongest skeptics of climate change. (Gosar insists he has at least one ally, but won’t say who it is.)

It all begs the question: Who is this guy?

Here are five things to know:

1) Gosar is best known for his push to impeach EPA Administrator Gina McCarthy (this month) and a bill to prevent lawmakers from flying first class using official funds (May 2014). 

Neither measure seems likely to go anywhere.

2) He crusades against environment regulation.

Gosar is one of the House’s leading critics of the EPA. And it’s not just on climate change — he is knee-deep in technical debates over environmental regulation as a member of the House Natural Resources Committee. Recently, Gosar has proposed measures to remove the Mexican wolf and the Sonoran desert tortoise from the endangered species list, block the EPA from donating funds to the United Nations Environment Programm, and to stop the EPA’s water rule clarifying its jurisdiction over ponds and streams.

3) He was elected in the original tea party wave.

Gosar unseated Rep. Ann Kirkpatrick (D-Ariz.) in 2010 after he was endorsed by Sarah Palin and Maricopa County Sheriff Joe Arpaio. (Remember that group that slept in their offices? He was part of it.) He’s proving his conservative bona fides this Congress, earning a 92 percent grade on the Heritage Action scorecard compared with 77 percent in the 113th and 79 percent in the 112th.

4) Still, he doesn’t make headlines as a rabble-rouser. 

Gosar might be a member of the Freedom Caucus, but compared with some of his peers, he’s rarely identified as a troublemaker for House leadership. Gosar did vote against Boehner for speaker this year, but in 2013, he voted for him.

5) He is Catholic and attended a Jesuit college.

A dentist by trade, Gosar earned his degrees from Creighton University in Omaha, a Jesuit school founded in 1878. He calls himself a “proud Catholic.” “If the Pope wants to devote his life to fighting climate change then he can do so in his personal time. But to promote questionable science as Catholic dogma is ridiculous,” Gosar wrote at Townhall.