AP Photo/J. Scott Applewhite

Special Counsel Robert Mueller departs the Capitol after a closed-door meeting with members of the Senate Judiciary Committee about Russian meddling in the election and possible connection to the Trump campaign, in Washington, Wednesday, June 21, 2017. 

Amidst floods, nuclear threats, and white nationalist violence, the latest disclosures from Special Counsel Robert Mueller’s probe of Russian interference in the 2016 election would be easy to overlook.

But the news that Trump allies last year sought the Kremlin’s help with a Moscow real-estate deal, and voiced hopes that it would boost his presidential campaign, moves the Russia scandal into new territory. Trump’s most hard-core loyalists may not care, but the broader GOP electorate is starting to pay attention, and that should worry Republicans facing midterm elections next year.

Russia is not the only factor fueling GOP unease, but there’s evidence that Mueller’s investigation is hurting Trump’s support within his party. Between March and June, the percentage of Republicans who said it was at least somewhat likely that Trump’s campaign associates had improper contact with the Russian government rose from 25 to 40 percent, one CBS News poll found.

In that same poll, a full 75 percent of Republicans said Trump should not try to stop Mueller’s investigation. And 56 percent of respondents from both parties said they thought Mueller’s investigation would be impartial, with 63 percent disapproving of Trump’s handling of the matter—his worst ranking on any issue.

Republican disenchantment is at least partly responsible for the recent decline in Trump’s approval rating, which Gallup now places at 35 percent. A recent Pew Research Center survey also found that nearly a third of GOP respondents agree with Trump on only a few or no issues, and nearly six in ten say Trump should listen more to Republicans who have experience working in government. Among Republicans, 19 percent also said they did not like his conduct, though the survey did not address Russia specifically.

“He will continue to have his core, he will continue to have a majority [among Republicans], but it will be a shrunken majority,” says John J. Pitney Jr., a professor of politics at Claremont McKenna College. Voters aren’t “focusing on any particular angle” of the Russia story, Pitney adds. “Rather, it’s the cumulative effect of all the stories adding up to a picture of a corrupt president.”

The latest Russia developments, reported in both The Washington Post and The New York Times, cast the problem of Trump’s business conflicts in a new light. Trump faces numerous lawsuits over his failure to divest from his business empire, including allegations that he has violated the Constitution’s Emoluments Clause, which bars elected officials from accepting anything of value from foreign interests.

To be sure, the steady stream of stories about foreign visitors to the Trump Hotel in Washington, D.C., may be starting to lose their shock value. The recent Russia disclosures go beyond mere conflicts, however, and raise questions about a possible quid pro quo. During last year’s campaign Trump business adviser Michael Cohen reportedly emailed Dmitry Peskov, a longtime lieutenant to Russian President Vladimir Putin, to ask for help reviving stalled plans to build a Trump Tower in Moscow. Russian American businessman Felix Sater also reportedly trumpeted the deal’s potential to boost Trump’s campaign, emailing Cohen: “Our boy can become president of the USA and we can engineer it.”

Cohen reportedly never heard back from Peskov, and the Moscow Trump Tower was never built. But these disclosures raise the stakes for Trump. The probe already had brought forth questions about collusion, fueled by the disclosure that the president’s son and many of his top aides met with a Russian lawyer last year in hopes of collecting dirt on Hillary Clinton. Now the question is whether team Trump engaged in outright corruption, by promising favors to Putin in exchange for help building a tower in Moscow.

Most Republicans on Capitol Hill, presumably fearful of angering Trump’s right-wing base, have resisted Democrats’ calls to aggressively investigate the president. As if to prove the extent of GOP loyalty, House Republican Ron DeSantis, of Florida, unveiled a measure this week that would block Mueller’s funding after a six-month period, and would bar him from investigating any matters prior to June of 2015, when Trump launched his presidential campaign.

But Mueller continues to move forward aggressively, last month ordering a raid on the suburban Virginia home of former Trump campaign manager Paul Manafort, and this week issuing subpoenas to Manafort’s spokesman and to his former lawyer. Mueller is also reportedly investigating Trump for obstruction of justice. And Trump, far from thanking the GOP leaders who are giving him cover, has taken to openly attacking his fellow Republicans on Capitol Hill.

The Russia probe holds dangers for Democrats, too, who risk being accused of overreach if they push too hard for Trump’s ouster—just as House Republicans were when they impeached President Clinton in 1998. But when it comes to midterms, the fortunes of the party in power are invariably tied to those of the incumbent president. Congressional Republicans who fail to take the allegations against Trump seriously may soon find that they cannot escape the fallout.