AARP is now if it was not at it's birth, a Leftist organization. They backed Obamacare just to make money off their insurance. 50+ people join for discounts and then AARP uses their money for Leftist causes.
There are other Seaoned Citizen groups that are Conservative, such as the AMAC, Association of Mature American Citizens.

I dropped AARP back when they were fighting Bush 43's plans to reform Social Security for people under 50. I, a Fed, asked them if they would help our fight against the GPO, and WEP. (Government Pension Offset and "Windfall Pension Exclusion". Misnamed rules that lower the amount of Social Security that a Fed earned in private industry and the amount of spousal Social Security. They said they had no need for retired or working Feds thought the cuts were just fine. So, I let my membership lapse. I am in NARFE and AMAC.