Hillary Clinton’s running mate, Tim Kaine, defended the Democratic nominee’s health, firing back at GOP nominee Donald Trump for the unfounded rumors about her health.

{mosads}At a Tuesday night rally in Lancaster, Pa., Kaine, who officially became part of the ticket last month, said he “can’t keep up” with the former first lady, who’s been on the campaign trail for 17 months.

“She is one tough lady and her health is beyond question,” Kaine said.

The Virginia senator’s comments come as Trump has raised questions about Clinton’s health, saying earlier this month in a speech about terrorism that she “lacks the mental and physical stamina to take on” the Islamic State in Iraq and Syria (ISIS). Breitbart News, the conservative site whose chairman recently joined Trump’s campaign as its CEO, has also published stories about these rumors.

Last week, an NBC report revealed that Trump’s longtime doctor spent five minutes writing his letter last year that claimed the real estate mogul would be the healthiest president ever elected and that he wrote it while a limo sent by Trump’s campaign was outside the doctor’s office. Following that report, Trump on Sunday said that both candidates “should release detailed medical records.”

“Hillary Clinton has released a detailed doctor’s report about her health just like other presidential candidates do that go into all of the health issues that anybody would want to know because you got a right to know,” Kaine said.

“Donald Trump, well I don’t think it’s fair to say that’s he’s issued any kind of a health report,” he continued, reading excerpts of the Trump doctor note, amid laughter from the audience.

Kaine argued that voters are entitled to know about the health histories of presidential candidates.

“This whole campaign has got the feeling of the next Trump con to it,” Kaine said. “Shame on us if we let him get away with this.”