For Donald Trump to become president, the difficult road begins at the Republican convention

He trails Hillary Clinton in most battleground states. Some of the leading figures in his own party refuse to endorse him. The top Republican in the Senate won’t even say if he considers him qualified to be president.

Still there is a path, albeit narrow, for Donald Trump to win the White House.

It starts on the shores of Lake Erie when the Republican National Convention opens Monday in Cleveland’s downtown sports arena.

The gathering and its huge national audience will afford the presumptive GOP nominee one of his last best chances to hoist himself into serious competition with Clinton before three debates scheduled this fall.

Unlike those sessions, events over the next several days will be largely under Trump’s control — at least within the confines of the red-white-and-blue-filled convention hall. (The streets outside are another matter.)

So to give himself a decent shot in November, Trump needs to pull off a triumphant, gaffe- and glitch-free convention.

“It’s his opportunity to hit the reset button,” said Don Sipple, who served as an image impresario for Bob Dole, the GOP’s 1996 nominee and the last Republican to enter a presidential convention in such difficult straits.

It will also be an opportunity for Trump’s freshly chosen vice presidential running mate, Indiana Gov. Mike Pence, to introduce himself to a national audience and try out his new, considerably higher-profile role.

For all his travails, Trump has several things working to his advantage, which has kept his race against Clinton, the presumptive Democratic nominee, reasonably close.

The economy is in less-than-stellar shape. Surveys show most voters believe the country to be headed on the wrong track. Not least, Clinton suffers a number of liabilities, including persistent doubts about her trustworthiness and personal integrity.

To take advantage, though, Trump must do something he has yet to achieve, even as he stormed past a field of far more politically practiced rivals to seize the GOP nomination: convince a majority of voters that he has the steadiness of temper, solidity of character and capacity for leadership they desire in a president.

“He’s an unguided missile,” Sipple said. “He has to become serious and substantive and drop the bombastic belligerence so that people see him in a new light.”

In private conversations, Republicans who support the Manhattan business mogul and are helping to plan the convention acknowledge the considerable work that needs doing before the gavel falls Thursday night.

For Trump “the large hurdle is ‘can I see him as president of the United States?’ ” said one strategist for the campaign, who asked not to be identified so as to speak more candidly. “That means different things to different people.”

For some, the strategist said, that means reassurance that Trump possesses the cool head and steady hand needed to serve as president. For others it means learning there is more to his agenda than provocative stands such as banning Muslims from coming to America or building a wall between the U.S. and Mexico.

Conventions are, at bottom, enormous television extravaganzas devoted to a single purpose — building the nominee up to heroic proportions and tearing down the opposition. For all of Trump’s unconventionality, the gathering in Cleveland will be no different.

The program will include testimonials from family members, a sprinkling of sports and other celebrities and a handful of Trump’s vanquished opponents, including Wisconsin Gov. Scott Walker, who quit the race early, and Texas Sen. Ted Cruz, his longest-lasting and fiercest foe.

Republican leaders will take their customary spot on the podium, among them House Speaker Paul Ryan, who will preside over the convention, and Senate Majority Leader Mitch McConnell — even though the Kentucky lawmaker, when pressed, pointedly declined to say if he thought Trump was qualified to sit in the Oval Office.

As he takes the convention stage, Trump faces the twin challenges of a daunting political map and changing electorate.

While national opinion polls show him running close to even with Clinton, what matters more is their standing in individual states; the November election, after all, is a series of discrete contests in each of the 50 states as well as the District of Columbia.

Democrats have carried 18 states and Washington, D.C., in the last six presidential elections, giving the party’s nominee 242 of the 270 electoral votes needed to win the White House.

Republicans have won 13 states for a total of 102 electoral votes; tossing in others that typically lean the GOP’s way, Trump can probably count on just under 200 electoral votes.

To win, he needs to carry all the states that Republican Mitt Romney won four years ago and then several more he lost, including Florida, Ohio and at least one large industrial state in the Northeast or Midwest.

The latest batch of polls show Trump behind in North Carolina — a state Romney carried — effectively tied with Clinton in Ohio and Florida, and trailing in every other state he would likely need to win, including Pennsylvania, a prime target because of the large number of older and white working-class voters who formed Trump’s base in the primaries.

Adding to his difficulties, Trump has largely shunned two of the standard practices of presidential campaigning, organizing and TV advertising, leaving him at a considerable disadvantage as he plays catch-up.

He badly lags Clinton’s on-the-ground operation in major battleground states — in Ohio, for one, Democrats have roughly twice the staff as Republicans — and has ceded the advertising airwaves since the two candidates effectively clinched their party nominations in May and June, respectively.

Clinton has broadcast more than 30,000 TV spots in Florida, Ohio, North Carolina and other states likely to decide the presidential contest, according to an Associated Press tally. Trump has aired none.

Apart from a difficult map, Trump faces a demographic challenge: the face of the American electorate is rapidly changing, a shift led by voters — young people, Latinos, Asian Americans — put off by Trump and his racially charged rhetoric.

At this point in the race the only group that Trump surpasses Romney’s performance of four years ago is among white men lacking a college degree; their turnout lagged considerably in 2012 and to stand any chance of winning Trump needs to spur a significantly greater number to the polls in November.

At the same time, he has to run much stronger than polls now suggest among women, college-educated white men, Latinos, Asian Americans and African Americans.

Accomplishing those twin feats — courting one without alienating the others — would be a challenge, even for a politician far more skilled and supple than Trump.

If experience holds, Trump should get a boost in opinion polls after the convention is over, though that may be negated by a rise in popularity for Clinton after the Democrats hold their gathering next week in Philadelphia.

That leaves three debates and, of course, any number of surprise developments, such as Friday’s terror attack in Nice, France. How those play out politically — moving voters toward the presumed steadiness and reliability of Clinton, or driving them toward the tough talk and pugnacious promises of Trump — is unknowable at this point.

That elevates the importance of Cleveland.

“A coherent convention speech, a well-behaved candidate and then a strong, disciplined performance in the debates could put him in a position where the desire for change is just enough to carry him across the finish line,” said Sipple, the political media strategist.

That may sound like threading a needle. But it’s the daunting reality Trump faces.

mark.barabak@latimes.com

Twitter: For more political news and analysis follow me @markzbarabak

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