Americans are increasingly tired of Donald Trump's presidency. More than half of the voters polled in June by the Democratic-aligned firm Public Policy Polling said they believe the president is an inveterate liar. Forty-seven percent said they would back Trump's impeachment and removal from office.

Which is why, as the evidence grows that the Russian government helped the 2016 Trump presidential campaign, Trump's critics are expressing outrage that Republicans in Congress continue to defend the president.

"How long can the rest of the Republican Party prioritize partisanship and agenda over decency and patriotism?" the Washington Post's editorial board asked on Tuesday.

The comedian John Oliver seemed to answer that question the next day when, talking about the revelation that Trump's son Donald Jr. met last summer with a Russian agent, he said: "It seems serious, but do we live in a world devoid of consequences now? I forget where we are in human history."

The answer to both WaPo's and Oliver's questions: be patient.

There are indeed still consequences in today's political world, but it takes longer for them to come about, thanks in part to the fracturing of the media into partisan camps. Some Republicans are as unhappy about this as Democrats.

Trump certainly does retain significant support from GOP members in the U.S. House of Representatives and the U.S. Senate. But that support is probably as thin as it is wide.

From the outside, Republican backing of Trump appears monolithic, so much so that it can be easy to forget that a lot of GOP leaders really don't like the president. Consider: Sen. Ted Cruz this week did verbal jiu-jitsu to avoid criticizing Donald Jr. for his apparent willingness to conspire with a hostile foreign country to help elect his father. Facing questions about the Trump administration's relationship with Russia, Cruz offered nonsense answers. "I think that we have had eight years of [President] Barack Obama showing nothing but appeasement towards Russia," he said, responding to a question about whether Trump was too cozy with Vladimir Putin's government.

Cruz, remember, is the man Trump labeled "Lyin' Ted" during last year's Republican presidential primaries, whose wife Trump threatened to "spill the beans" on, whose father Trump accused of helping Lee Harvey Oswald assassinate President John Kennedy. Cruz once called Trump a "sniveling coward."

Why would the senator from Texas defend Trump, considering their ugly history? It's called self-preservation. (In the political world, self-preservation can usually be safely filed under Moral Cowardice.) It comes down to this: Being a member of Congress is a good gig. Few people who've enjoyed the perks want to give up the job. Sen. John McCain was just re-elected at age 80. The legendary Strom Thurmond didn't retire from the Senate until he was 100, five months before he died.

Cruz is up for re-election next year.

So is Republican Speaker of the House Paul Ryan. Back when Trump was on the verge of securing the GOP presidential nomination last year, and Democratic nominee Hillary Clinton looked like a safe bet to win the election, Ryan made a big show of saying he was "not there yet" when asked about endorsing Trump.

Then he found himself stalked by angry Trump supporters every time he returned to his district in Wisconsin.

He's now very much "there." When pressed last month about Trump demanding loyalty in February from FBI Director James Comey and telling Comey to go easy on former National Security Adviser Michael Flynn, Ryan's response was that the president "is new at this. He's new to government. And so he probably wasn't steeped in the long-going protocols that established the relationships between DOJ, FBI, and White Houses." (Trump, of course, fired Comey for refusing to back off on the Russia election-conspiracy investigation.)

This week, when Ryan was asked whether he would accept a meeting with an agent from a foreign government who offered damaging information on a political opponent, as Trump's son did, Ryan responded: "Look, I am not going to go into hypotheticals."

Ryan is thinking about the 2018 mid-term election, which he knows is not hypothetical. Every Republican holding elected office is afraid of Trump's diehard supporters. Driven by class resentments and, in some cases, racial animus, these "Trumpkins" make up somewhere around a quarter of the electorate, and they are not moved by traditional GOP stands on economic and social issues. They see Trump as their hero, as the only person in Washington, D.C., who has actually taken their interests to heart.

Cruz, Ryan and their colleagues know these pseudo-Republicans will turn out to vote in the 2018 primaries. They dare not anger them. So they fall back on one or more easy responses: Democrats are being hysterics; it's Obama's fault; Trump is new at government and doesn't know how to act; Russian meddling in the U.S. election is serious, so let's give Special Counsel Robert Mueller the room he needs to do a proper investigation.

That last answer is the important one. (And flying under the radar, by the way, is New York State Attorney General Eric Schneiderman, who's reportedly investigating Trump and the Trump Organization for financial crimes.) If Mueller eventually comes forward with smoking guns even hotter than Trump Jr.'s meeting -- and backs them up with indictments -- we might finally see Fox News turn away from Trump, thus knocking down the president's popularity among Republican voters. Right now, the cable-news behemoth is floating the notion that Trump campaign collusion with Russia, if it actually happened, wouldn't be criminal, that it actually wouldn't be a big deal. Its audience isn't entirely buying it. Seventy-two percent of GOP voters support the president, according to a late-June poll from CBS News. That's down from 83 percent a month before.

Fox News, like Trump himself and the GOP majority in Congress, will keep a close eye on such poll numbers. If the conservative press starts backing away from the president, then it's Katy bar the door. Republican members of the House suddenly will be quite interested in fleshing out articles of impeachment.

-- Douglas Perry