So, what does it mean when the professional tea leaf readers move a congressional race from a Likely Republican status to a Leans Republican status?

Well, we are about to find out.

That's exactly what Sabato's Crystal Ball, one of the nation's leading trackers of races at the state, congressional and presidential levels, did this week with Ohio's 1st Congressional District, which has been held by Republican Steve Chabot in all but two of the past 25 years.

This time around, Chabot faces a Democratic opponent in Aftab Pureval, who has caused a sensation in southwest Ohio Democratic politics ever since he won an unexpected, upset win over the Republican Hamilton clerk of courts, Tracy Winkler.

Until this charismatic, articulate, young and talented politician came along, nobody – nobody – could beat a Winkler. Having the Winkler name meant automatic election for decades.

But, even given Pureval's skills, there was a collective mini-gasp among the political class when the Crystal Ball, published by Larry J. Sabato, director of the University of Virginia's Center for Politics, published a list of 26 ratings changes, all in favor of the Democrats.

Democrats were ecstatic pointing to it as more evidence that 2018 is going to be a "wave year" for Democrats – as mid-term congressional elections often are – and that the Republicans are going to have to preserve their majority in the House dragging President Trump behind them like a sack of wet cement.

Republicans look at it and shrug their shoulders – particularly in a district like Ohio-1, where, two years ago, Trump won by only six percentage points and Chabot was re-elected with an 18-percentage point margin.

The district is a gerrymandered mess, thanks to the Republicans in the Ohio General Assembly who re-drew it after the 2010 Census. It is made up of most of western Hamilton County and parts of the county north of the city.

And, in 2010, the Republicans in the legislature gave Chabot the gift that keeps on giving: Warren County, one of the fastest growing counties in Ohio, with just oodles and oodles of Republican voters.

Chabot had spent most of his congressional career fighting off tough challenges from Democrats – none more tough than 2008 when Democrat state representative Steve Driehaus rode the Obama wave to defeat Chabot. Two years later, though, Driehaus was gone and Chabot had won back his House seat.

The addition of Warren County automatically puts any Democrat at a distinct disadvantage when he some to challenging Chabot.

So why the rating change? And is it really a cause for hub-bub?

Kyle Kondik, the managing editor of the Crystal Ball and an Ohioan, gave WVXU four reasons why Ohio 1 has gone from Likely to Leaning:

"The national environment and history suggest Democrats are positioned to make gains."

"Pureval should be able to run a credible race."

The district (at least the Hamilton County part of it) has been competitive in good Democratic years "and it probably is a place where there are a significant number of Trump skeptics, perhaps even among those who voted for him."

And, finally, Kondik said, "Chabot's fundraising has been somewhat weak."

So, Steve Chabot is cruising for a bruising this year, right?

Well, no, not necessarily.

"Put it all together,'' Kondik told WVXU, "Chabot is still favored, just not by as much as before."

"Favored, just not by as much as before." The essential difference between Likely and Leaning.

Alex Triantafilou, the chairman of the Hamilton County Republican Party, clearly believes this rating change business is over-rated.

"You don't win an election based on punditry,'' Triantafilou said. "You win it on the ground."

Triantafilou said a lot of people in his party are taking this Chabot-Pureval race seriously and are flocking to Chabot's side to help him with fundraising and organization.

"There's no question it's a real race,'' Triantafilou said. "There is real concern in the party about the House flipping to the Democrats.

"But what Steve Chabot has going for him is how well-liked he is in the party,'' the county party chair said. "I feel good about Steve's race. Will he have to work? Yes. But you won't find candidates who work harder than Steve."

Pureval, Triantafilou said "has no affinity for the district."

"He moved into the 1st District and changed his voting address the morning he announced he was running,'' Triantafilou said. "Steve's spent his life in that district."

A shift in a political newsletter's rating "is not the real ground-shaking event,'' said David Niven, assistant professor of political science at the University of Cincinnati. "The ground-shaking event is having a credible challenger in the first place."

To pull off a takeover of the House, Niven said, the Democrats are going to have to field "credible candidates" like Pureval in districts all over the country.

The only way the party out of power fails in a "big wave" election is by failing to field "plausible candidates," Niven said.

"The 1st District certainly has one in Aftab,'' Niven said. "There was never really a pause in his campaigning, after he won the clerk of courts race."

Pureval, Niven said, "decided that this was his time; this was his window of opportunity. You don't get to lose many of these before you are no longer considered a credible candidate."

The Democrat can win Hamilton County, but the real test for him is how many GOP voters – probably upscale, highly-educated voters – are not Trump fans. The more he pulls away from Chabot, the better Pureval's chances become.

It is, Niven said, "in some ways the ultimate test of gerrymandering."