IOWA CITY - If you had to conjure a living version of the word "improbable," look no further than South Bend Mayor Pete Buttigieg. When he launched his presidential exploratory effort last January, even some Hoosier Democrats thought he was overly ambitious.

Heading into the sixth month of this experiment, Mayor Pete now faces a crucial sequence that will go along way in determining whether he's an epic dreamer, on the brink of a presidential nomination, or a slot on the national ticket. 

After a series of critically acclaimed town halls on CNN, Fox News and MSNBC and dozens of network talking head appearances, Buttigieg will find himself on the debate stage with the frontrunners, the old folks of the Democratic Party: Joe Biden, Sen. Bernie Sanders and Sen. Elizabeth Warren. Biden has dominated with a Real Clear Politics polling composite lead approaching 20% but has had a tormented week capped by a sudden shift on the Hyde Amendment after supporting it for decades. Sanders has faded, Warren is on the rise, and Buttigieg has leveled off in the polls after flirting with the so-called "top tier" nationally and Iowa and New Hampshire polls. He lags behind in South Carolina, where he has virtually no support from the crucial black voters.

Polls in early summer 2019 are simply mileposts. Frontrunners often fade, and while Warren has risen in polls over the past two weeks, what a candidate really wants to do is be begin a crescendo late next fall, with momentum carrying into the early caucuses and primaries

The debate late this month that begins this head-to-head comparison sequence that will extend into fall. Buttigieg has accomplished an important element to a presidential portfolio: He discusses issues with knowledge, wit, empathy and humor. He is establishing a generational contrast. He has captured the imagination of thinking Democrats, independents and even Republicans I know.

Appearing at the California Democratic convention this past weekend, Buttigeg framed his strength by urging the party to move "forward," explaining, "Democrats can no more keep a promise to take us back to the 2000s and 1990s than conservatives can keep promises to take us back to the 1950s. The riskiest thing we can do is to try too hard to play it safe."

With the generational seeds sown, Buttigieg will next need to create the aura that he belongs on the big stage, in the midst of the frontrunners. If he's successful, he will burst away from the 5-7% polling range he currently occupies and become a double digit contender. Then he can hope to catch fire next November, just as Barack Obama, Bill Clinton and Jimmy Carter did with what were initially seen as long-shot candidacies.

He's beginning to provide issue stances beyond the storyline the early sequence of his candidacy established. The town halls are also fleshing out positions. Pressed by MSNBC's Chris Matthews last Monday, Buttigieg said that if he was in the U.S. House, he would back impeaching President Trump.

He nuanced any criticism of House Speaker Nancy Pelosi for slow walking impeachment, saying, "Even though I have revealed myself to be ambitious in that I’m a young man running for president, I’d also think twice before offering strategic advice to Nancy Pelosi.”

Asked by a woman why people of her gender should vote for a man for president (and I hear this aversion from many of my Democrat friends), Buttigieg referenced Hillary Clinton, saying, “We ought to have a woman in the White House right now.”

Buttigieg is also directly taking on President Trump, calling him out on issues ranging from ducking the Vietnam War, to the Memorial Day embarrassment when Trump advance team members attempted the hide the USS John McCain from his view, lest there be a conspicuous temper tantrum.

Winning a presidential nomination is a complex endeavor. A nominee has to capture the imagination of a large swath of voters. This person must frame issues that resonate and excite, amply and effectively communicate, provide contrasts, raise upwards of $100 million, and, of course, the intangible: The nominee will need some luck.

In Mayor Pete's case, he's got to hope that Trump will scare Democrats away from nominating a "socialist" like Sanders or someone too shrill over over-caffeinated like Warren. He must hope that Trump stays mired in the 41% range for job approval. There will be elements beyond anyone's control. What if the 78-year-old Biden has a health scare or zones out during a speech? What if Trump demonstrates he can get under the skin of Warren?

We won't know how this story will turn out by the time of the Fourth of July fireworks. But what we are likely to discover in the coming month or so is whether this ambitious Indiana mayor has the right stuff for the times, can separate himself from the Democratic field, and rhetorically take the fight to a president who acts and rules in unprecedented ways.

 The columnist is publisher of Howey Politics Indiana at www.howeypolitics.com. Find Howey on Facebook and Twitter @hwypol.