Dan Nowicki

The Arizona Republic

As Democratic presidential nominee Hillary Clinton's campaign spends money on TV ads in red-state Arizona, Republican nominee Donald Trump on Sunday resumed his feud with one of Arizona's Republican senators.

U.S. Sen. Jeff Flake appeared on two national Sunday morning public-affairs programs — CBS' Face the Nation and CNN's State of the Union — to discuss Trump, whom he has thus far refused to endorse because of the candidate's harsh anti-illegal-immigration rhetoric and lack of serious policy proposals. Flake also has said Trump's controversial statements have put Arizona in play for the Democrats this year.

Flake, a member of the bipartisan "Gang of Eight" who collaborated on an immigration-reform bill that passed the Senate in 2013, also criticized the intense immigration speech that Trump delivered Wednesday in Phoenix.

"Some people said it was hardening. Some said softening. I say it was just confusing," Flake said on Face the Nation.

Flake said that Trump's proposal to build a border wall and make Mexico pay for it is not a serious policy proposal and that most Arizonans know that.

The senator has long been critical of Trump, and even personally confronted him in a July meeting in Washington, D.C. And while Flake didn't make much news on the Sunday shows, he apparently again got under Trump's skin.

Later Sunday, Trump fired off two angry tweets at Flake.

Flake did not respond to a request for comment on Sunday. However, he got some strong support on Twitter from Evan McMullin, a former CIA operative who is running for president as an independent.

Clinton responded to Trump, too, noting on Twitter that, "There's going to be no one left in Washington for Trump to work with who he hasn’t insulted."

But Trump was backed up by former state Sen. Kelli Ward, who came up short Tuesday in her primary challenge against U.S. Sen. John McCain, R-Ariz.

In what could be the opening shot in the 2018 Republican primary for Flake's Senate seat, Ward retweeted Trump's attack and wrote: "I agree - how about you?"

"Time for him to go..." Ward added in another tweet aimed directly at Trump.

Besides his fight with Flake, Trump also has battled with McCain, even going so far last year as mocking McCain's record in the Vietnam War. Trump also has called McCain weak on immigration and veterans issues. But, ultimately, Trump endorsed McCain's re-election. McCain also is supporting Trump as his party's presidential nominee.

Follow Dan Nowicki on Twitter: @dannowicki