American support for capital punishment has increased after hitting a four-decade low in 2016, according a Pew poll released June 11.

It comes as the U.S. Supreme Court is considering a petition that seeks to topple the ultimate punishment as well as challenges to how it’s carried out against the aging and ill, in particular.

The rise in support for executing murder convicts—now at 54 percent, compared to 49 percent two years ago—is mostly due to increased backing among political independents, the poll said. 39 percent of the country is opposed.

Republicans still overwhelmingly support the penalty, at 77...