These midterm elections are hard to game out.

That's because there are a lot of factors that could cancel each other out, and there is no single issue that appears to be breaking through.

"Frankly, it is about volatility," said a Republican operative, who spoke on the condition of anonymity to be candid about strategy. "It's very volatile out there."

That volatility starts at the top with President Trump. The president sometimes vacillates from one position (might not believe the U.S. intelligence assessment on Russian election interference) to another (he means he does believe it).

His trade policies, which many worry amount to a war, have introduced a new level of volatility. Elected officials in his own party have been speaking out against this president's tariffs because farmers and manufacturers in their states have been hurt by it.

The president, though, breathed a much-needed sigh of relief Wednesday when he brought European Union Commission chief Jean-Claude Juncker out to the Rose Garden — just as Secretary of State Mike Pompeo was reaffirming the veracity of the U.S. assessment on Russian interference to a panel of senators. They announced that the EU would buy more soybeans and liquefied natural gas from the U.S. (There was no mention of the thorny issue of cars. Hello, Michigan!)

It was important timing for the president, given the pressure he — and his party — is under. The negative effects of tariffs have been real, with his administration going so far as to propose a $12 billion bailout for farmers. (Think about that for a moment: Trump is asking his party to ditch its ideals on two fundamental things — free trade and bailouts.)

And Trump's poll numbers in key upper Midwestern states, where he did so well in 2016 largely because of his trade message, have taken a hit. His job approval rating is under 40 percent in Michigan, Minnesota and Wisconsin, according to Marist polls conducted for NBC News. Even fewer said he deserved re-election — just 28 percent in Michigan, 30 percent in Minnesota and 31 percent in Wisconsin.

But one thing is consistent in this year-and-a-half of a Trump presidency — you just never know what the next week will bring.

The daily, or weekly, tit-for-tat is not what wins midterm elections. They are usually about something, about an issue or two that drives the electorate. In 2006, it was about the Iraq war. In 2010, it was health care.

Ordinarily, this far into the cycle, something would have emerged. Republicans hoped in 2018, it would be tax cuts. Democrats have tried to push health care and wages.

"Democratic candidates need to focus on lowering health care costs and increasing wages to meet cost of living," said a Democratic operative, who spoke on the condition of anonymity to freely discuss party strategy.

But so far not much has really stuck.

"One thing we've seen in these issues polls is there isn't a dominant issue, per se," the Republican operative said. "It's all very muddled. ... When a story pierces that news bubble for three to five days, you know it's different."

The operative said the Mueller Russia probe has been the "stasis for cable news," but, he maintains, hasn't registered with swing voters. Democrats believe the Russia saga has created a cloud of chaos around Trump.

The Russia factor

For as much as Democratic strategists want to push health care — and that is what Democrats say their candidates are focused on in swing districts — that wasn't the message du jour being pushed by House Democratic leaders this week.

Instead, House Minority Leader Nancy Pelosi introduced a resolution condemning Trump's comments in Helsinki with Russia's Vladimir Putin, in which he cast doubt on the U.S. intelligence assessment that Russia interfered in the 2016 elections.

"On Twitter and in the Beltway, you're seeing lots of jumping around from message to message, but not in the districts that matter," said the Democratic operative.

Republicans privately conceded that Pelosi's measure was likely intended to jam them up and drive a wedge between various GOP members, who disagree with Trump's strategy toward Russia.

And for good reason. An NPR/PBS NewsHour/Marist poll out this week found Russia is a losing issue for Trump right now: Two-thirds of Americans think he hasn't been tough enough on Russia; a majority thinks he has done something untoward in his personal dealings with the country; and 7-in-10 believe the U.S. intelligence assessment about Russian election interference over Putin's denials.

Two-thirds also want Mueller to be allowed to complete his investigation — including a majority of Republicans.

Russia and the potential fruits of the Mueller investigation are the shiny metal objects of liberal politics. It's what's talked about at cocktail parties, where members of "The Resistance" allow themselves to imbibe on hopes of Trump being escorted from office.

That inevitably leads to talk of the "I" word — impeachment.

But the only ones talking about impeachment this week were Republicans — not of the president but of Deputy Attorney General Rod Rosenstein. Members of the conservative House Freedom Caucus introduced legislation to impeach Rosenstein for what they see as obstruction of their requests for documents and information related to the 2016 election investigations.

"For nine months, we've warned them consequences were coming, and for nine months we've heard the same excuses backed up by the same unacceptable conduct," Mark Meadows, head of the Freedom Caucus, said in a statement Wednesday. "Time is up and the consequences are here. It's time to find a new Deputy Attorney General who is serious about accountability and transparency."

Ohio Rep. Jim Jordan added, "The DOJ is keeping information from Congress. Enough is enough. It's time to hold Mr. Rosenstein accountable for blocking Congress's constitutional oversight role."

House Speaker Paul Ryan said Thursday he disagreed with the resolution and would not bring it up for a vote.

Minutes later, Jordan announced he would be running for speaker.

Immigration over tax cuts so far

The GOP was supposed to be banking on tax cuts, their signature legislation of Trump's first year, to help in these elections. But while Republicans and outside groups have run some ads on tax cuts, it has been limited.

Instead, in many cases, especially in the primaries, they have been harping on immigration.

Georgia Secretary of State Brian Kemp, for example, won Trump's endorsement and the Republican nomination for governor Tuesday after running ads like this:

"I've got a big truck, just in case I need to round up criminal illegals and take 'em home myself. Yep, I just said that."

His more soft-spoken GOP opponent, Lieutenant Governor Casey Cagle, said of the race in leaked audio, "This primary felt like it was who had the biggest gun, who had the biggest truck, you know, and who could be the craziest."

But Republicans say they feel good about making the case on immigration. The NPR/PBS NewsHour/Marist poll shows Americans don't agree with the direction Trump is taking the country on immigration, but that's not how Republicans plan to message the fight.

They say they will try to tag Democrats, especially in moderate districts, with the new "Abolish ICE" movement — pushed notably by upstart Democratic Socialist Alexandria Ocasio-Cortez from New York — which now has even some potential Democratic presidential candidates' support.

Coming up in less than two weeks is a special election in the right-leaning 12th Congressional District in Ohio. In that race, there has again only been a limited focus on tax cuts from Republicans and more on trying to tie the Democratic candidate to the left wing of the party on immigration.

Moderate Republicans feel the heat on health care

Health care has consistently popped toward the top of polling of the most important issues in this election, something Democrats noticed early on. Immigration and the economy, though, have been right there, too.

President Trump speaks in Iowa, which has been hit hard by tariffs from other countries issued in retaliation to Trump's tariffs. Trump brought with him new "Make Our Farmers Great Again!" hats. (Evan Vucci/AP)

Republicans hope Trump's positive marks on the economy will blunt Democrats' enthusiasm — and their criticism of the Trump administration undermining the Affordable Care Act, something that could lead to higher premiums this fall.

Republicans are plotting to use some of Democrats' more extreme positions — like single-payer health care — put forward by Democrats in more liberal states, against other, more moderate, candidates,

"We feel good about the contrast with single-payer," the Republican operative said. "We plan to make that an issue."

Less noticed on Capitol Hill this week: It was some Republicans looking to push health care fixes right before they headed home for the extended summer recess to campaign. One bill, introduced by Rep. Peter Roskam of Illinois, deals with expanding access to Health Savings Accounts. The other, introduced by Rep. Erik Paulsen of Minnesota, would repeal the medical device tax. That passed Tuesday, with some Democrats voting for it, too.

Not surprisingly, both Republicans are in toss-up re-election races.

The Trump factor might be the most important factor

The one thing that is clear is the same thing that's been clear for a year and a half — the most important factor in 2018 is President Trump himself.

The NPR/Marist poll showed Trump is unpopular, with a 39 percent job approval. Still, he retains his base (85 percent Republican approve of the job he's doing), and he hit his highest level of those saying they strongly approve of him (25 percent) in the poll.

But — and it's a big but — a record 44 percent strongly disapprove of the job he's doing.

"Trump's approval is like barbells," the Republican operative said, "nothing is in the middle."

Historically, a president's popularity is a pretty good indicator of which direction things are going. Of course, the wildcard is that Trump has defied historical political odds before, and his approval rating is about where his favorability ratings were during the presidential election that he won.

But Trump's numbers in the suburbs, especially with suburban women, have to alarm Republicans. Fifty-seven percent of suburban women said they strongly disapprove of the job he's doing in the NPR/Marist poll. And many of the key House races to be decided this year run through the suburbs.

That doesn't mean moderate Republicans can simply abandon Trump, though. In midterms, activists dominate, and running away from Trump might be a worse choice.

"There are ways to use him, no matter what district he is in," the GOP operative added.

The economy does give Republicans something to tout about the president's legacy. And that's no small thing.

Democrats will be pointing out wage stagnation, as Republicans did when the economy was improving under President Obama's watch.

As for Trump and Russia and the other issues that dominate in the Beltway, Democrats say they are content to let Trump make the case for them.

"Here's the thing: no one is going to talk about Trump more than Trump," the Democratic operative said, adding, "He put a dark cloud over himself and his party, and I do think it matters having that dark cloud hanging over."

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