Former Wisconsin governor Scott Walker is once again working closely with Vice President Pence on debate preparations and serving as Pence’s foil in practice sessions, effectively playing the role of Sen. Kamala D. Harris (D-Calif.), according to two people familiar with the sessions who spoke on the condition of anonymity because they were not authorized to speak publicly.

When reached by phone on Thursday, Walker declined to comment about any ongoing work with the vice president. “All I can say is that I worked with him four years ago and was happy to help,” Walker said. “That’s it.”

The two people said Walker, a conservative who became friendly with Pence when both served as Midwestern governors, is involved in debate prep, including discussions and meetings this week.

One of the people familiar with Pence’s prep work said several debate-related meetings were slated to be held Thursday.

A Pence spokesperson could not be reached for comment.

In 2016, Walker was Pence’s stand-in for Sen. Tim Kaine (D-Va.), who was the Democrats’ vice-presidential nominee that year. Washington lawyer Robert Barnett was Kaine’s stand-in for Pence.

The vice-presidential debate between Pence and Harris will be held Oct. 7 at the University of Utah. It is being organized by the nonpartisan Commission on Presidential Debates and will be 90 minutes in length. USA Today Washington Bureau Chief Susan Page will serve as the moderator.

Walker has recently targeted Harris on Twitter and on television, potentially previewing what Pence could use as a line of attack next month. “She & @JoeBiden need to side with law enforcement and denounce radicals,” Walker wrote this week, referring to the unrest in Kenosha, Wis., following the shooting of Jacob Blake, who is Black, by a White police officer.

Last week, Walker cast Harris as a liberal on the environment. “Manufacturing and agricultural jobs would be devastated by that radical plan that Bernie Sanders and others are pushing and that Joe Biden has got to give a wink to it,” he said on Fox News.

Walker was elected governor of Wisconsin in 2010 and 2014 and became a favorite of GOP activists as he battled public sector unions. He unsuccessfully ran for the Republican presidential nomination during the 2016 election cycle. He then made a bid for a third term but was defeated in 2018 by now Wisconsin Gov. Tony Evers (D).