Looks like President Nixon supported it, at least publicly, but I’d think he would have been concerned that young voters would tend to favor the Democrats, especially with the draft still in place, as he faced reelection in 1972. Anything in the White House tapes or other sources to indicate that, behind closed doors, Nixon would rather have seen the 26th Amendment fail?
Richard Nixon is sitting on a stool, and is about to give a press briefing. He’s dressed in bell-bottoms, a paisley shirt, a vest, and a headband, and is holding a guitar. He’s saying [paraphrasing], ‘And to demonstrate that I’m not supporting the 26th Amendment just to get the 18-year-old votes, I’ve written this song…’
Agree that all of Nixon’s actions with regards to earlier attempts would indicate he supported the idea. Perhaps he felt that most 18 years olds wouldn’t vote, which turned out to be the case.