Former Fox News employee Mike Huckabee led all declared and potential Republican presidential candidates with 70 minutes of airtime on the network in May. Sen. Rand Paul, who was second in total time with 53 minutes, led all candidates with 12 appearances.

As we did during the 2012 presidential cycle, Media Matters will publish regular updates on the amount of interview time Fox News gives each declared and potential Republican presidential candidate. The network provides candidates with an invaluable platform with which to raise their profiles and pitch themselves to Fox's conservative audience.

This cycle, the Fox Primary may be more consequential than ever.

In a May 30 column for the Los Angeles Times, Doyle McManus argued that Fox News chief Roger Ailes “will decide which candidates can compete in Republican presidential primaries next year.” In a move that has raised the ire of some conservative activists and members of the presidential field, Fox News announced that the first primary debate -- to be hosted on the network on August 6 -- will feature a maximum of 10 candidates, chosen based on polling.

According to McManus, “One side effect, GOP strategists say, is that during the next two months, those candidates will be even more desperate to boost their name recognition -- by appearing on Fox News.” He added, “Fox won't exactly be judge, jury and executioner, but it will be rule-maker, gatekeeper and moderator.”

The Fox Primary has been well underway since President Obama's second inauguration. An April Media Matters study found that potential Republican presidential candidates had already made more than 800 appearances on Fox News' evening and primetime programming and Fox News Sunday.

In May, the 16 declared and potential Republican presidential candidates made a combined 68 appearances on Fox News, totaling more than 8 hours of airtime. Rick Perry was the only one to not appear on the network during the month.

Megyn Kelly's The Kelly File featured both the most candidate appearances and the most total interview time, though it should be noted that these numbers are inflated slightly by a special her show aired on May 22 featuring a compilation of previous interviews Kelly had done with various Republican candidates.

Most Total Airtime: Mike Huckabee (1 hour and 10 minutes)

Most Total Appearances: Rand Paul (12 appearances)

Fox Show With The Most Total Candidate Airtime: The Kelly File (2 hours and 40 minutes)

Fox Show With The Most Candidate Appearances: The Kelly File (19 appearances)

Softball Question(s) Of The Month: In Fox & Friends' only interview with Christie, co-host Brian Kilmeade asked only a single question on “the controversy with the bridge and various other things” :

KILMEADE: What did you learn over the last year where you had the controversy with the bridge and various other things about yourself and about who your friends are?

Methodology

For this study, we used FoxNews.com's “2016 Presidential Candidate Watch List.”

Media Matters searched the Nexis database and our internal video archive for all guest appearances on Fox News Channel and Fox News Sunday for the 16 declared and potential presidential candidates in question: Jeb Bush, Ben Carson, Chris Christie, Ted Cruz, Carly Fiorina, Lindsey Graham, Mike Huckabee, Bobby Jindal, John Kasich, George Pataki, Rand Paul, Rick Perry, Marco Rubio, Rick Santorum, Donald Trump, and Scott Walker.

For programs where a transcript was unavailable, we reviewed the raw video.

Note: Starting in August, we added all weekend programming to the study. For full data including weekends and a revised methodology, click here.

Charts by Oliver Willis. Additional research by Media Matters' research staff.