PHOENIX — As Republican Sen. Jeff Flake returned to Arizona this week during a congressional break, he was constantly reminded of the tightrope he must walk as he gears up for his 2018 re-election bid.

Protesters on the left followed him around with a giant inflatable chicken whose hair style was patterned after President Donald Trump. Their message: Don’t be a chicken and stand up to the president on issues like health care. On the right, a former tea party activist ripped him on a daily basis over his moderate stances.

Flake faces a tough test next year that is emblematic of the challenges many Republicans will encounter in the first midterm election of the Trump presidency. The left is energized on issues like health care, and the right is targeting politicians like Flake who have been outspoken in their criticism of the president.

The junior Arizona senator was a frequent critic of Trump during the 2016 campaign and has said he didn’t vote for him. In his visit to Arizona week, he touted his support of the North American Free Trade Agreement — a deal Trump took the first steps to renegotiate or dismantle last month. But Flake also points out his support of Trump’s Supreme Court and cabinet picks.

“I think people appreciate independence,” Flake said during a wide-ranging interview this week. “I’ll support the president when he’s right and I’ll oppose him when he’s wrong.”

Flake faces at least one Republican challenger next year, former state Sen. Kelli Ward, and others are waiting in the wings, considering whether to jump in. They include state treasurer Jeff DeWit, an early Trump backer who ran the president’s campaign finances and would surely get big backing from him. A Democratic opponent has yet to emerge.

Ward has taken aim at Flake for bucking his party’s right wing and backing immigration reform, dubbing him “sanctuary senator.” She also criticized him for the backing he gets from former GOP presidential candidate Mitt Romney, another Trump critic who is set to appear at a Flake fundraiser on Friday. Former President George W. Bush also came to Arizona for a recent Flake fundraiser, and he can count on the loyal backing of fellow Arizona Sen. John McCain.

“In my last election I had somebody spend about $9 million, mostly painting me as out of touch with Arizonans on immigration,” Flake said. “That person got 20 percent of the vote after spending $9 million. We beat ’em by 49 points.”

Flake points to McCain’s easy 2016 re-election win, where he too abandoned Trump after a 2005 tape emerged of Trump making lewd remarks about women. Arizona remains a solidly red state, but independents now outnumber Democrats and Republicans.

“(McCain) garnered I think, 250,000 more votes than the president did. Won the state by 14 against his opponent – the president won by 3½ points,” Flake said. “So I think Arizonans are more independent.”

But it’s the vulnerability from the left that is likely more problematic for Flake. He’s a target of opponents of the Affordable Care Act repeal, who drag out the inflatable chicken at many of his events.

“I think he’s absolutely vulnerable if he votes to repeal the Affordable Healthcare Act,” said U.S. Rep. Ruben Gallego, a rising Democratic star from Phoenix who has been critical of the House-passed repeal and replace plan. “Health care is a very personal thing, we’ve learned it as Democrats. Republicans are going to learn the same thing if they pull this system out from underneath people.”

Flake has had a full schedule this week, appearing at businesses and events across metropolitan Phoenix, launching a push to defend NAFTA against a possible Trump pullout, making an appearance at a nuclear plant, speaking to business leaders and working to boost his campaign coffers. As of March 31, records show he had about $1.8 million on hand.

Flake avoided town hall meetings that have stirred up liberal voters and protesters like the one he faced earlier this year. At events before friendly crowds this week, like a Glendale Chamber of Commerce event Tuesday, he still got questions critical of repealing health care law.

Flake acknowledges the House-passed bill, under which congressional analysts estimate 23 million people will lose coverage, has no chance in the Senate. The Senate is now working on its own plan, but Flake won’t commit to backing it until he’s reviewed it.

Retired property manager Bill Morris was at the Glendale event and said he is worried about the effects of the repeal on his Medicare and on friends with other types of insurance. He said he wants Flake to stand up to Republicans who are pushing a repeal.

“I would tell him to vote his conscious and not his party,” Morris said. “This is the United States, he’s responsible to all of us, especially here in Arizona since he’s one of our two senators.”

Flake cites insurers fleeing the private marketplace as evidence that Congress has to act.

“For those who say let’s just keep the ACA as it is, that’s not possible. It’s not going to survive as it is, we know that,” flake said. “In Iowa, already, the only insurer there has indicated an intent to pull out. We’re going to have a lot of people with no choice at all.

At the same time, he’s aware of the big boost that an expanded Medicaid program under Obama provided in Arizona.

Arizona has seen more than 400,000 people get insurance, plus another 20,000 children under a plan known as KidsCare, under Medicaid expansion. Nearly all would lose coverage under the House plan unless the state embraces a massive tax increase, which is virtually impossible in the Legislature. About 200,000 people buy private insurance on the federal marketplace, and many would see dramatic changes there too and likely lose affordable coverage.

“With (Medicaid), particularly in those states that expanded, they’ve come to rely on that pretty quickly,” he said. “And it would be a big jolt to the budget and big problem for those who have coverage if it were to end immediately.”