Cindy McCain recorded a video message for Tuesday's Democratic National Convention, paying tribute to an "unlikely friendship" forged between former Vice President Joe Biden and her late husband, Sen. John McCain (R-Ariz.)

Why it matters: Cindy McCain, who self-identifies as GOP-aligned, but "liberal on social issues," is the latest Republican to lend her voice to the Democratic convention, after four conservatives including former Ohio Gov. John Kasich spoke Monday.

My husband and Vice President Biden enjoyed a 30+ year friendship dating back to before their years serving together in the Senate, so I was honored to accept the invitation from the Biden campaign to participate in a video celebrating their relationship.https://t.co/Y6XOnBC1IW

— Cindy McCain (@cindymccain) August 18, 2020