The welterweight division has one less world champion.
Lamont Peterson, who held the WBA's "regular" welterweight title, vacated the title after sending a letter to the governing body. In that letter, Peterson said he "does not want to be an obstacle for the rest of the fighters of the ranking who have the objective of fighting for the belt."
The WBA statement does not mention anything about the "regular" title being fought for. The governing body, known for having numerous world champions in the same weight class, has been trying to determine only one world champion. Peterson's resignation as champion now gives the WBA 10 weight classes with only one world champion.
Peterson hasn't fought since winning the WBA title in February when he beat David Avanesyan via unanimous decision. Peterson was once the unified WBA and IBF junior welterweight champion before moving to welterweight. Before the win over Avanesyan, Peterson last fought in late 2015, when he beat Felix Diaz. Peterson has been boxing as a pro since 2004, amassing a 35-3-1 record (17 KO).
Regarding who could be in line to face Keith Thurman, the WBA's "super" welterweight champion and the WBC champion, there is no mandatory challenger. The WBA recently released its newest rankings and have WBA Asia champion Tewa Kiram as the No. 1 ranked boxer, followed by Danny Garcia and then by WBA Intercontinental champion Lucas Matthysse.
Now the remaining world champions at 147 pounds are Thurman, Errol Spence Jr. (IBF) and Jeff Horn (WBO).