A conservative group called Republicans for the Rule of Law has launched a $1 million ad campaign urging GOP lawmakers to support an investigation into President Donald Trump’s efforts to persuade the Ukrainian president to investigate political rival Joe Biden’s son.

The ads running on TV and digital platforms are aimed at 20 Republican members around the country.

“This an abuse of power by the chief executive of our country. He won’t stop unless Republicans like you stand up and say that it’s wrong,” the ad’s narrator says. “Senator Alexander, your voice is critical. Stand up for the country and stand up for the rule of law.”