Wisconsin Gov. Scott Walker (R) announced Monday that he was suspending his campaign for the White House, urging other candidates to follow suit. (Reuters)

Wisconsin Gov. Scott Walker's decision to end his presidential bid months before a single vote had been cast in the 2016 race signals the challenge posed by a personality-heavy contest dominated in recent months by reality TV star and real estate mogul Donald Trump.

Walker's bland Midwesternness had long been touted by his campaign as the key to his appeal in the contest -- a regular guy amid a sea of candidates who simply didn't empathize with the average voter in Iowa and New Hampshire. And Walker showed enough personality -- particularly in a forceful address at an Iowa Freedom Summit event in January -- that the political establishment and, to a certain extent, Republican voters (especially in Iowa) seemed to buy what the Wisconsin governor was selling.

But, that calculation was pre-Trump. From the day Trump entered the race in mid-June, Walker struggled to find his footing in a race in which the "star" was no longer Jeb Bush -- a relatively conventional opponent -- but rather an entertainer who would say and do anything to draw attention.

Republican presidential candidate Donald Trump traveled to Iowa to campaign in the key state where, according to a new poll, he has surged ahead of the pack of Republican presidential candidates. (Reuters)

As Trump went from a novelty act to the star of the presidential campaign, Walker's 'Joe Average'-schtick began to feel like an echo of a race that was no longer being run.  Crowds packed in cheek-to-jowl to listen to Trump regale them with the famous people he knew and the "big" deals he had cut. Walker just kept telling the same story about how he got his sweaters at Kohl's.

A "bigness" gap emerged -- never more so than at the two debates, the first in Cleveland and the second last week in California.  Walker, despite his relative prime position on the stage -- a vestige of the national polling bump he got after that speech at the Iowa event way back in February -- seemed diminished when standing among his rivals for the nomination.  And it wasn't just Trump whose persona towered over Walker; Bush, Marco Rubio, Carly Fiorina and Chris Christie all just seemed -- and I know this is a loaded word --more presidential than Walker.  In the second debate last week, Walker spoke for the shortest period of time of any candidate on the stage; his campaign complained about the lack of speaking time but part of running for president is being able to butt your way into conversations and making moments. He did neither.

Speaking of making moments, the Walker campaign did everything it could to find a moment in which his supposed "true self" showed through. But, even when they found one -- Walker shouting down a protester at the Iowa State Fair seemed like it might do the trick -- the candidate could never repeat the performance. It was a one-off rather than a trend.

By the time the Trump boom appeared (appears?) to be fading, it was already too late for Walker.  He had cratered in Iowa and nationally; a CNN/Opinion Research poll released on Sunday showed Walker with less than one percent of the vote nationally.


(Philip Bump / The Washington Post)

As the chart above shows, it wasn't only Walker who struggled in the summer (and early fall) of Trump.  Bush and Rubio -- among others -- took a hit. But Walker took the brunt of the Trump assault; he went from relevant national contender to non-existent.

Why? Because, unlike, say Bush or Rubio -- or even Christie -- Walker's appeal in the race was always an inch deep.  His rise, as I noted above, was almost entirely predicated on a single speech in Iowa in which he out-performed low expectations and a resume that on paper (as resumes do) looked quite good. Walker filled a void created by Bush as the electable conservative. (By the time Walker began to surge, lots of conservative members of the GOP establishment had concluded that Bush was not one of them and had begun to look elsewhere.)


Wisconsin governor and Republican candidate for president Scott Walker reacts during a campaign event at a diner in Amherst, New Hampshire, in this file photo taken July 16, 2015.  REUTERS/Dominick Reuter/Files

But Walker never really performed like the candidate many establishment Republicans wanted him to be -- or thought they saw in that moment in Iowa. Support quickly gained can be quickly lost -- especially when there's a new bright shiny thing that is much brighter and shinier than you.

The legacy of Walker's candidacy may well be that personality matters a lot more in presidential politics than in Wisconsin politics.  Walker's steady-hand-at-the-tiller message, which handed him three victories in four years in the Badger State, never really translated to the national stage.

But that might undersell the blame Walker and his team deserve.  Being vanilla is not a message.  Ignoring Trump is not a solution. Refusing to adjust is not an answer.  And, in the end, hoping a candidate without much pizzazz or personality -- or at least the ability to show that pizzazz or personality publicly -- might be the person to rally Republicans to his cause looks like a major mistake.