Patricia Richardson has taken off the gloves in her challenge to Ken Howard for the presidency of SAG-AFTRA.

The “Home Improvement” star, in an email sent Thursday to the union’s 160,000 members, accused Howard and his Unite for Strength allies of poor performance in recent contract negotiations, spending on “lavish” offices and cloaking union operations in secret. Although the tone of the missive was cordial and did not name Howard — opting instead to attack “current leadership” — the email carried a long list of accusations of incompetence.

Richardson, who is heading the self-styled progressives on the Membership First slate, took a cordial tone in the message and said she would not make “wholesale changes” to committee chairs and members just because of party differences.

“We need the expertise of everyone we have,” she said. “However, we do feel the current leadership has been unable to deliver true gains.”

About 140,000 ballots went out last week to the SAG-AFTRA membership, with results due to be tabulated on Aug. 20. Howard won elections in 2009 and 2011 for the SAG presidency, and in 2013 won the post against Esai Morales in the first election for the merged SAG-AFTRA, running each time as the head of the moderate Unite for Strength slate — which has dominated politics in the performers unions since 2009.

On June 1, he announced that he would seek re-election with Jenny O’Hara as his running mate for secretary-treasurer. Howard’s current endorsement list includes Alec Baldwin, Lewis Black, Bryan Cranston, Sally Field, Tom Hanks, William H. Macy, Octavia Spencer, Jeffrey Tambor and Lily Tomlin.

Richardson’s message accused SAG-AFTRA leaders of not keeping up with the changes in the business.

“Current leadership is failing to represent effectively our members in negotiations with basic cable, pay cable and new media companies,” she said. “In the past, many in our union were slighted in home video/DVD profits and told, ‘Because it’s a new evolving medium, we’ll have to wait until it matures.’ In the end, the studios made billions, while SAG-AFTRA members were left with pennies. We hope to avoid repeating the mistakes of the past.”

Richardson also accused Howard and his allies of incorrectly asserting that they have clinched network rates with new media. “They don’t tell you there are no network residuals on the big budget shows, no residuals at all on the first year and increasingly unlivable residuals after that,” she added.

She attacked Howard and his allies for failing to complete a merger of the still-separate SAG and AFTRA health and pension plans — a key point in Howard’s successful campaign to persuade members to support a SAG-AFTRA merger in 2012.

“Your health plans and pensions are part and parcel of belonging to a union in the first place,” Richardson said. “Although there’s the possibility of a merged health plan, there is no plan in the foreseeable future to merge the pension plans. This means that your earnings and years of work are still being split between SAG and AFTRA. That leaves many of our members falling between the cracks, with insufficient years of work in either plan to be vested.”

Richardson also blasted Howard and his allies for secretive practices.

“Are you aware that members on the national board are given copies of the union’s financial reports mere minutes before the meeting begins?” she said. “Leadership quickly summarizes what is inside the packet of information and hastily collects the copies before the board meeting can continue. Information should be provided freely and openly, with plenty of time in advance. I would be surprised to hear if any other board operates like this.”

Richardson, who’s been on the national board for the past two years, said she disagreed with the decisions to close 10 regional offices while renting a “lavish” 55,000-square-foot office building in New York for the newly merged union building for 100 employees.

“According to someone on their own team, this was completely unnecessary, as the old SAG building was big enough for them to use,” she said. “Not only did they forget to budget for furnishing this building, but also, never sublet the old SAG and AFTRA buildings; so, the two spaces sat empty and unrented for over two years until we recently spent over a million to buy ourselves out of one of those leases. We still pay rent on the other empty building.”

Richardson concluded the email by asserting that she will work with her opponents if elected.

“Let’s not waste energy in being fearful, divisive or angry, and instead build a strong bipartisan board which works doggedly to do what needs to be done, with democracy and transparency restored,” she said. “That is my hope.”