The evolving watchdog group behind the ballot challenge to Trump

No matter how the Supreme Court rules on Donald Trump's challenge to a Colorado court ruling barring him from the state's primary ballot, the case has already been a win for one group.

Oral arguments in the case Thursday represent the culmination of a long and sometimes fitful evolution for Citizens for Responsibility and Ethics in Washington, or CREW, the watchdog group that initiated the case. The group helped find the plaintiffs who brought the case in Colorado and funded the lawsuit arguing that Trump is ineligible for the presidency because he engaged in an insurrection by promoting the storming of the Capitol by his supporters on Jan. 6, 2021.

Its pivotal role in the case comes amid intensifying pressure from donors for technically nonpartisan groups to take unambiguous and aggressive sides in a polarized Washington.

Since it was founded in 2002, CREW,...