Frank Luntz, a conservative pollster and political commentator, believes Republicans will lose control of both the House and the Senate in the 2018 midterm elections––and that President Donald Trump's diminishing poll numbers are to blame.

“If Donald Trump wants to keep the Republican Congress, he has to differentiate when he’s attacking Congress in general versus the Republicans in Congress," Luntz said yesterday during an appearance on Fox News. “Differentiate when he’s attacking the press versus when he feels he’s not getting a fair shake.”

“I think the Republicans are in deep trouble in the House and the Senate as well. If the election were held today, frankly, I think Republicans would lose both.”

Luntz further criticized the president's use of social media, saying his tweets are a distraction from the challenging year the Republicans will face.

“It’s his own tweets that are causing so much of the trouble,” Luntz said, suggesting that Trump should “remove about a third of them.” He suggested the president should turn his focus to "the economy and taxes."

35 Senate seats are up in the 2018 elections, and Democrats need to defend their existing 26 of those seats and win two additional ones if they wish to attain a majority. In the House, 435 seats are up for election in November. House Republicans currently hold 238 seats. Democrats hold 192 and are predicted to gain more.

And Luntz isn't the only prominent conservative to have noticed the challenge ahead.

In an interview last week with Kentucky Today, Mitch McConnell (R-KY), the Senate Majority Leader, acknowledged the troubles Republicans face:

This is going to be a challenging election year. We know the wind is going to be in our face. We don’t know whether it’s going to be a Category 3, 4 or 5... I’m hoping we can hold the Senate. And the principle reason for that, even if we were to lose the House and be stymied legislatively, we could still approve appointments, which is a huge part of what we do.

Senator Ted Cruz (R-TX) issued a warning of his own last month during a talk with conservative radio host Hugh Hewitt:

Look, I think this is a volatile election. I think it could go a lot of directions. In one scenario, the economy is booming, we have a lot of conservatives show up. We could have a terrific election in November. We could win five, six, seven Senate seats. We could have a large functioning majority in the Senate. The flip side, if conservatives are complacent, we know that the left is going to show up. The extreme left, they’re angry. They’re filled with rage. They hate the President. And mark my words, we are going to see historic turnout from the extreme left in November, which means if conservatives stay home, we have the potential, we could lose both houses of Congress. We could end up with a Speaker Pelosi and a Majority Leader Chuck Schumer. In Texas, if conservatives stay home, if we rest on our laurels, we could see Texas turn blue. We could see every statewide official in the state becoming a Democrat. Now that’s long been a Democrat pipe dream. I don’t believe it’s going to happen. But the best way to make sure it doesn’t happen is for conservatives to show up.

Cruz suggested that the day Nancy Pelosi (D-CA) becomes the Majority Leader would mark the rise of "the extreme left":

That’s what the extreme left wants. They want to impeach the President, and they want to stop the entire agenda that’s been moving forward of tax cuts, cutting regulations, protecting the Constitution, protecting our fundamental rights. If we want to keep that going, we’ve got to show up.

Meanwhile, Wisconsin Governor Scott Walker also sounded an alarm, warning his constituents that a "blue wave" would hinder all progress made in the state.

Many prognosticators have warned against the House flipping but Luntz is the first to warn against the Senate.

In an op-ed for The Hill, Shermichael Singleton, a political commentator and Republican political strategist, warns that "with midterms quickly approaching, 2018 generic congressional numbers indicate that Republicans should be concerned this November":

As Republicans attempt to cling to power and Democrats seek to take it, the GOP must be concerned about the ongoing special counsel investigation, which has been a dark cloud over the White House. As Robert Mueller goes on with no end in sight, it’s a waiting game, leaving many holding their breath wondering who is next to be indicted and whether or not it will be a current White House official. It’s a waiting game that has everyone on the edge of their seat.

When you couple the Mueller investigation with the president’s frequent outbursts on Twitter and the various scandals from within the White House and the various agencies headed by his cabinet secretaries, it is obvious that chaos has touched nearly every aspect of government and its institutions. With key voters such as Independents being turned off and minorities being emboldened to become more active participants in the political process, this could be a combination too difficult for Republicans to overcome.

If Republicans lose the House in November, will it be a wake-up call? Will they finally begin to question some of the president’s actions and words or will they continue to go along out of fear of one of his Twitter attacks? As a conservative, I certainly want Republicans to do well, but at some point, reality will hit home, and when it does, it should come as no surprise.

Similarly, a Washington Post report from earlier this morning cites several Republicans who've shared increasing fears of losing House control.

“Our donors will often say we need to do everything we can to hold onto the Senate, because there’s a chance we may not be able to hold the House,” said Steven Law, a former McConnell chief of staff who runs a super PAC called the Senate Leadership Fund.

Oil industry executive Dan Eberhart concurred: “If I had to bet right now, I’d say we lose the House,” he said, adding it is “galactically important” to hold the House if Republicans wish to confirm nominations from the White House.