While Donald Trump has been extraordinarily attentive to his political base of supporters, they alone will not carry him to a second term, according to Fox News journalist and commentator Chris Wallace.

“You can’t do it, because there are just not enough votes in the base. It appears that from most of the polling that 35, 40 percent of eligible voters are what you would call ever Trumpers, solid red core Trump supporters,” Wallace said. “That’s not enough to win an election. So he’s going to have to expand his base. And one of the things that a lot of political experts have been wondering about is — the president seems to have a lot of leeway with the base.”

Unlike many other Fox hosts, Wallace is seen as a much more non-partisan political observer and analyst.

Wallace acknowledged that Trump’s 2016 campaign promise that Mexico would pay for a wall along the border between the two nations has been “largely dispensed with now and it doesn’t seems to have bothered his base as long as he keeps faith on the idea of building the wall.”

Trump is in the midst of trying to construct that wall using military funds, having declared a “state of emergency” at the southern US border.

But even with his loyal base, it’s not enough, Wallace said.

“You got to expand it to independents. You have to expand it to suburban Republicans, suburban women, persuadable Democrats,” Wallace added.

Many of those constituencies Wallace said Trump needs to attract fled the Republicans in the 2018 midterm elections, causing the US House to flip to Democratic control.

Trump would have to find a way to bring those groups back into the GOP fold.

“You look where he won in 2016, in the suburbs, in the so-called blue wall of upper Rust Belt states like Michigan and Pennsylvania and Wisconsin. You can’t just do it with the base. You’re going to have to expand,” Wallace said.

Although Trump won Michigan, Pennsylvania and Wisconsin in 2016, contributing to his Electoral College success, he won those states narrowly with a combined margin under 100,000 voters.

Ultimately, Wallace said, Trump is going to have to portray whomever becomes his opponent as the Democratic nominee as unpalatable and unacceptable.

“One of the things I think he’s counting on is that he’s either going to be able to portray or the Democrats in fact will nominate someone who is so far to the left, the president would say a socialist, that it’s going to make it easier for him,” Wallace said. “He doesn’t have to pivot as far to the center because he’ll say the Democrats have moved so far to their extreme left.”