Hall of Fame first baseman and Giants legend Willie McCovey said he wants to see Barry Bonds join him in the Hall and contests Joe Morgan’s letter encouraging voters to reject players linked to steroids.

“I just think it’s a sin he’s not in there,” McCovey said of Bonds, the ex-Giants outfielder who holds the season and all-time homers records. “If anybody deserved to be in the Hall of Fame, it’s Barry.”

Bonds is on the ballot for the sixth time after receiving 53.8 percent of the vote last year. Votes cast by the Baseball Writers’ Association of America are due Sunday, and 75 percent is required for enshrinement.

On Nov. 21, a day after the ballot containing 33 names was released, Morgan’s letter was emailed to voters by the Hall of Fame, pleading with them not to support players who admitted using steroids, flunked drug tests or were mentioned as users in the 2007 Mitchell Report, which published findings of an MLB investigation headed by former Sen. George Mitchell.

Morgan, the Hall’s vice chairman and a member of its board of directors, wrote that some Hall of Famers wouldn’t attend induction ceremonies “if steroid users get in,” refusing to share a stage with them.

“That letter Morgan wrote sure is not going to help Barry,” McCovey said, “but I’m glad to hear a lot of the writers say the letter is not going to influence their vote because I know a lot of it is aimed at him. I wasn’t too happy about it.

“You’re naive if you don’t think it was aimed at Barry.”

Nonetheless, Bonds seems to be gaining ground. In an online vote tracker produced by Oakland’s Ryan Thibodaux, 33 percent of the ballots have been made public, and Bonds sits at 72.9 percent, though his percentage early in last year’s voting was higher than where he actually finished.

McCovey contacted Morgan, a Hall of Fame second baseman, after the letter came out.

“Joe and I are really close, too. He’s one of my best friends,” McCovey said. “I went back and forth with him on it. I told him how much I disagree with him. I told him I won’t let that hurt our friendship. But don’t include me on the ones who are not going to show up if they go in.”

Besides Bonds, players on the ballot with links to performance-enhancing drugs include Roger Clemens, Gary Sheffield, Manny Ramirez and Sammy Sosa.

Though Morgan wrote that he hopes “the day never comes when known steroid users are voted into the Hall of Fame,” it’s possible it already happened, but those players might not have been caught because their dealers weren’t subject to investigations, including by the government.

Asked why be believes Bonds should be in the Hall of Fame, McCovey said, “Do I have to answer that? You talk to anybody who played against him at that time, they’ll say he was the best hitter they ever saw in their lives. Those are his peers talking.”

As for Bonds’ link to PEDs, McCovey said, “Guys took things ever since baseball existed. It may not have been steroids, but guys took things like those greenies and stuff so they could play the next day. You’re telling me everybody is clean as a whistle? You played against guys who were doing the same thing he was doing, so what the heck?”

Bonds can be on the ballot as many as 10 years. His year-by-year percentages have gone from 36.2 to 34.7 to 36.4 to 44.3 to 53.8.

John Shea is The San Francisco Chronicle’s national baseball writer. Email: jshea@sfchronicle.com

Twitter: @JohnSheaHey