Rich Lowry: Don’t root for a primary challenge to Trump

Former Massachusetts Gov. William Weld addresses a gathering during a New England Council 'Politics & Eggs' breakfast in Bedford, N.H., Friday, Feb. 15, 2019. Weld announced he's creating a presidential exploratory committee for a run in the 2020 election. (AP Photo/Charles Krupa)The race for 2020 is taking shape, although there are still significant unknowns, including whether Donald Trump will get a serious primary challenge.

Trump's dominance of the party begins with his lockdown support of the right, forcing any primary challenger to the left. This isn't fertile territory. Self-identified moderates and liberals are only a fraction of the party, and it is grass-roots conservative…