Eliza Collins

USA TODAY

WASHINGTON — Sen. Jeff Flake went against the president and now the head of the Republican National Committee warns that could lead to him losing in 2018.

Last week, the Arizona Republican released a new book in which he slammed his own party for supporting President Trump. But Republican National Committee Chairwoman Ronna Romney McDaniel reminded the conservative that two Republicans who didn't support Trump last year lost their elections.

McDaniel appeared on conservative radio host Laura Ingraham’s show. Ingraham, a defender of the president’s, said the Republican base is frustrated with lawmakers who go against the president. The comments were first reported by CNN Tuesday.

McDaniel agreed, saying the message from the grass roots is: “Congress needs to support this president.”

Ingraham said Flake would lose his re-election in 2018 because the base would be unhappy that he doesn’t support Trump.

McDaniel responded by pointing to two Republicans who did not support Trump during the 2016 election and lost their bids for Senate, Rep. Joe Heck of Nevada and incumbent Sen. Kelly Ayotte of New Hampshire.

Heck and Ayotte’s losses should serve as a “cautionary tale” for Flake, McDaniel said.

“I will say if you look at 2016, the senators that did not support the president, and let's look at Joe Heck and Kelly Ayotte, they fell short in those Senate races, so there is a cautionary tale there because voters want you to support the president in his agenda,” McDaniel said.

While Heck and Ayotte did lose, Sen. Rob Portman of Ohio and Sen. John McCain of Arizona both pulled support from Trump and won their 2016 races.