Ramesh Ponnuru: Why Republicans fear challenging Trump in 2020

A lot of Republicans still believe in the power of competition. A poll in November indicated that 40 percent of them, and 72 percent of all Americans, would like to see President Donald Trump face a primary challenge. But Republican politicians, even those who have strong objections to Trump, have been inhibited by the conventional wisdom that running against Trump in the 2020 Republican primaries would be a suicide mission.Trump is in a very strong position for renomination, as I have written i