LA CROSSE, Wis. — For a few hours, the unofficial Labor Day start to the fall presidential campaign centered around Wisconsin, as Vice President Mike Pence tried to poach Democrats in this Mississippi River town and Senator Kamala Harris sought to rally the Democratic base in Milwaukee.
But their dueling events at opposite ends of this increasingly pivotal state — as well as Joseph R. Biden’s visit to another battleground, Pennsylvania — were soon overwhelmed by a force as strong as any current: President Trump’s thirst for attention.
The only member of the two tickets not to be on the campaign trail Monday, Mr. Trump abruptly called a White House news conference and then used it to air a range of personal and political grievances. He called his opponents names — Mr. Biden was a “stupid person” and Ms. Harris was “not a competent person.” Yet more notable than his usual partisan insults was his extraordinary attack on the country’s senior military officials.
Defending himself for a fifth straight day following a report in The Atlantic that he ridiculed America’s war dead, Mr. Trump suggested the accusations came from Pentagon leaders, whom he described as war profiteers.
“They want to do nothing but fight wars so that all of those wonderful companies that make the bombs, that make the planes, that make everything else, stay happy,” Mr. Trump said of the officers he commands, making no mention of his own choice for defense secretary, Mark T. Esper, who was an executive at the defense contractor Raytheon.
The broadside, coming after current and retired officers have been notably quiet about claims that the president described those killed in action as “losers,” only added more fuel to an explosive story line that many Republicans want Mr. Trump to put behind him.
For the purposes of the campaign, Mr. Trump’s preoccupation with the Atlantic article illustrated the limited value of the presidential bully pulpit in the hands of a candidate unwilling to drive a focused message.
Monday, after all, was poised to showcase a showdown between Mr. Pence and Ms. Harris, who were appearing together for the first time in the same state on the same day.
The vice president, joined by Labor Secretary Eugene Scalia, was hoping to appeal to the white working-class voters along the state’s western border who supported Democrats for a generation before helping tip the state to Mr. Trump by less than a percentage point in 2016.
Standing before a group of employees at a regional utility company, Mr. Pence trumpeted the administration’s work on behalf of dairy farmers, claimed credit for the state’s booming economy before the coronavirus crisis and repeatedly attacked Mr. Biden and Ms. Harris by name.
Noting that Ms. Harris was one of only 10 senators to oppose the renegotiated North American free trade pact, because it did not do enough to address climate change, the vice president argued that she had put a “radical environmental agenda ahead of Wisconsin dairy and ahead of Wisconsin power.”
Though the company they spoke at employs some union members, neither Mr. Pence nor Mr. Scalia alluded to organized labor in their…