A Republican establishment worried about the rise of Donald Trump and Ted Cruz has two big problems: Support is divided among a number of their favored, centrist candidates for the GOP presidential nomination. And when support for those candidates is combined, it falls short of what’s likely needed to win.

The January and December Wall Street Journal/NBC News polls show no growth in aggregate support for the four principal establishment candidates: former Florida Gov. Jeb Bush, New Jersey Gov. Chris Christie, Ohio Gov. John Kasich and Florida Sen. Marco Rubio.

Adding the support totals for all those candidates in January yielded a sum of 26%. In December they had garnered 27%.

By contrast, Mr. Trump’s support in January was 33%—a larger share than the four establishment candidates combined.