New tonight: The U.S. Senate campaigns are continuing to wrangle over debates, with Democrat Beto O'Rourke re-upping his request for six showdowns and Republican incumbent Ted Cruz making clear he's still in no rush to face the El Paso congressman.

The two campaigns exchanged letters on the topic today, starting with O'Rourke's. His campaign manager, Jody Casey, wrote to senior Cruz aides to remind them of her April 24 letter inviting Cruz to participate in six debates, four in English and two in Spanish. Casey also reminded them she had asked to start coordinating the debates by May 10 and they didn't reply, even as the senator spoke publicly about his willingness to debate O'Rourke.

"I am therefore writing to reiterate our request to immediately begin coordination of six general election debates," Casey said, alluding to Cruz's comments after the April 24 invitation that he doesn't speak Spanish well enough to debate in it. "Because Senator Cruz recently indicated that he is uncomfortable debating in Spanish, our campaign would be happy to add two additional debates in English instead."

Cruz's campaign responded with a letter of its own from senior adviser Bryan English. He acknowledged both of Casey's letters and reiterated that Cruz is looking forward to debating O'Rourke.

"However, your arbitrary timeline for coordinating between the campaigns remains irrelevant to our decision-making process," English said. "We will let you know when we are ready to discuss the details of joint appearances."

For months, Cruz has indicated he's open to debating O'Rourke but hasn't committed to a specific schedule. In more recent remarks, Cruz has said he'll debate O'Rourke "closer to the election" when more people are paying attention.

The O'Rourke campaign's letter:

Letter -- 60 Days Later, No Debates by Patrick Svitek on Scribd

The Cruz campaign's letter:

20180709 Signed Reply to O'Rourke Campaign by Patrick Svitek on Scribd

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