Democratic gubernatorial candidate Andy Beshear received a big bipartisan boost on Monday with the endorsement from a longtime state legislator.

Republican state Sen. Dan Seum, of Fairdale, bucked the GOP to endorse Beshear, the state's attorney general, over incumbent Matt Bevin in the upcoming Kentucky gubernatorial election.

In a video posted Monday morning on Twitter, Seum stood with Beshear and said his endorsement "is not about partisan politics." He then ripped Bevin for his past comments about educators.

"This is about who is going to lead this state in the next four years," Seum said. "Today, we have a governor who has failed miserably in the pension issue and has spent the last year running around the state insulting everyone, including the four teachers in my family."

'So much is at stake': Kentucky teachers could play key role in Bevin-Beshear race

Seum, who represents parts of south Louisville and Bullitt County, has served in the legislature since 1982. He famously switched parties in 1999 from Democrat to Republican to give the GOP control of the state Senate.

Read this:Sen. Rand Paul offers to buy Ilhan Omar a ticket back to Somalia to 'appreciate America more'

Beshear used the endorsement to underscore his campaign stump speech, saying the 2019 contest "isn't about right versus left" but "about right versus wrong." He said he welcomes Seum's support and that there is room for all Kentuckians on his campaign.

Bevin campaign manager Davis Paine dismissed Seum's support for Beshear in a statement to the Courier Journal.

"If Sen. Seum wants to support sanctuary cities and abortion up until the moment of birth, that’s his decision to make," he said. "Gov. Matt Bevin has been endorsed by President Trump, the NRA, and Kentucky Right to Life.”

Former state Sen. Joe Bowen, who represented Owensboro, also blasted Seum for backing the Democratic nominee.

"Dan if you weren’t still serving only to pad your pension then maybe this would be a statement," Bowen tweeted. "In all due respect you need to go home and save the state some pension money... maybe the savings would go to a worthy state retiree."

Seum's decision to endorse Beshear is a reminder of Bevin's sometimes fractious relationship with the Republican-controlled legislature, as well as his controversial comments aimed at teachers.

Last year, for instance, the legislature condemned Bevin in a bipartisan resolution for suggesting teacher protests in Frankfort were likely responsible for children being poisoned or sexually assaulted because they weren't in school.

Beshear has made it a point on the campaign trail to say how Bevin is seen as a bully by many Kentuckians across party lines and even among his political allies.

Seum had been on the Senate Republican leadership team as caucus chairman until the 2019 legislative session. And he has voted for pension bills backed by Bevin.

Last week, for instance, Seum voted for Bevin's bill to give quasi-governmental groups such as local health departments and regional universities relief from higher pension costs. The bill was opposed by all Democrats and a few Republicans, who say it will cut pensions for many employees of those groups.

Seum also voted for a comprehensive pension reform bill in March 2018 that was backed by Bevin and strongly opposed by the Jefferson County Teachers Association and the Kentucky Education Association. That measure was later unanimously struck down by the Kentucky Supreme court for procedural reasons.

Reporter Tom Loftus contributed to this story.

Reporter Ben Tobin can be reached at bjtobin@gannett.com and 502-582-4181 or follow on Twitter @TobinBen. Support strong local journalism by subscribing today: subscribe.courier-journal.com.

Reporter Phillip M. Bailey can be reached at 502-582-4475 or pbailey@courierjournal.com. Support strong local journalism by subscribing today: courier-journal.com/philb.