(CNN) An activist and the owners of a New York city bakery teamed up to find a sweet way to pressure Republican senators to subpoena testimony from President Donald Trump's former national security adviser, John Bolton: With cake.

Colin Bishopp, the executive director for the environmental nonprofit PACE Foundation, worked with Brooklyn-based Butter & Scotch to send what they're calling "impeachment cakes" to the offices of 53 GOP senators.

So far, cakes have only been delivered to the offices of Republican Sens. Rob Portman of Ohio and Cindy Hyde-Smith of Mississippi. Texas Republican Sen. Ted Cruz's office turned his cake away.

Almost every cake had "Let Bolton testify" written at the bottom.

"We tried to come up with an example of something that everyone likes, something that every senator would have to agree is fundamentally good. All we could come up with is cake," Bishopp said. "Everyone loves cake! We figured that if Republican senators are going to ignore the facts being delivered to them by every other medium, why not try to reach them with cake?"

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