But he faces more daunting hurdles here in the West than perhaps any other region of the country, most significantly the traditional battleground states of Colorado and Nevada -- and possibly even Arizona -- as he attempts to chart his course to 270 electoral votes.
Trump will officially win the 1,237 delegates he needs to clinch the Republican nomination when California holds its primary. After riding his wave of anti-immigrant rhetoric to the top of the GOP, Trump and his allies have sought to shift the political conversation to his opportunities in the industrial Midwest. He has argued that he can galvanize blue-collar workers and Reagan Democrats in those areas to put states like Michigan, Ohio, Pennsylvania and Wisconsin into the GOP column.
But the questions the general election contest will hinge on is whether the enthusiasm for Trump among white, blue collar voters can overcome the anti-Trump fervor on the opposite side -- and whether Democratic front-runner Hillary Clinton can draw the same level of energy and enthusiasm from minority and younger voters that President Barack Obama did to build his winning coalition.
"One of the biggest cards in favor of Hillary Clinton is the vote against Trump, rather than the vote for her," said William H. Frey, a demographer at the Brookings Institution. "She has a lot of policies that are certainly friendly to Latinos... but I think the biggest thing that will energize them is Trump."
Because of that, Trump's industrial Midwest strategy may end up being more of a necessity than a choice given his soaring unpopularity among the fast-growing minority groups that are reshaping politics in the western states, as well as states like Georgia and North Carolina.
A Fox News Latino poll released Friday showed Clinton leading Trump among Latino voters 62% to 23%. A striking 74% of Latinos said they viewed Trump unfavorably.
Bill Whalen, a Hoover Institution research fellow at Stanford University, noted that even before considering Trump's vulnerabilities among Latinos, "Hillary Clinton walks into the 2016 election -- no matter how weak she might be as a candidate -- knowing she's probably going to have a minimum of 246 electoral votes in her pocket."
"To win a national election right now, (Republicans) have to run the table. They have to win states they lost to Barack Obama," Whalen said. "The problem for Republicans is when you cannot build support among Latino voters, more states come into play," he said listing Arizona, North Carolina and Georgia.
"Unless Republicans can figure out to way to reach out to minorities and take that 27% for Mitt Romney and build it up to 35% or 40%, they're going to be looking at a very hard time getting elected in the near future," he said.
Complicating matters for Trump, his strongest appeal has been to older white voters. He has higher negatives among white women than recent GOP nominees, making it harder to do well in younger states like Colorado and Nevada where single women have been pivotal in recent contests.
All of those vulnerabilities have sparked a debate over whether Trump may have to simply cede the west to the Democrats and focus on swaying rust-belt voters with his anti-establishment credentials, anti-trade, anti-Wall Street message.
"He's gotten what he can get out of the immigration issue. I think the trade issue is where he can make inroads against Hillary," veteran Republican pollster Neil Newhouse said.
Newhouse said it is "way too premature to figure out the path to 270," because there is no stability in the polling numbers. He expects them to swing wildly in battleground states over the next two months before the conventions.
"If it turns out we can't win Colorado and Nevada," said Newhouse, who was Mitt Romney's chief pollster in 2012, "the play goes to the rust-belt through Pennsylvania, Ohio and Michigan -- with Pennsylvania being really kind of a lynchpin. It's a Rust Belt, I-95 strategy -- and that would include North Carolina, Virginia."
Test for Trump
One key test for Trump this week out West is how he recalibrates on the immigration issue -- if at all.
At his rallies, he is still talking about the wall between the U.S. and Mexico, but he has been talking less about his plan to round up and deport some 11 million immigrants without papers in the style of the Eisenhower-era "Operation Wetback
Even if Trump does dial back his rhetoric to strike a more inclusive tone; he is unlikely to avoid angry clashes with protesters here in California like the ones he confronted during his recent visit to Orange County
Those confrontations were reminiscent of the kinds of protests California saw in the mid-1990s during the debate over the Republican-backed Proposition 187, which would have barred undocumented immigrants from accessing basic state services like public schools and non-emergency health care. (The Republican Party in California never recovered.).
Democrats and labor groups have also been hard at work in states like Arizona, Colorado, Nevada and California -- driving up voter registration and citizenship applications among Latinos who were angered by Trump's call for a wall between the U.S. and Mexico and his deportation plan.
Maria Elena Durazo, a longtime labor activist who is general vice president for immigration, civil rights and diversity at the labor group UNITE HERE, noted that she had attended a recent citizenship workshop in Las Vegas that was aimed mainly at culinary workers.
"We interviewed person after person," Durazo said, "and I would say 90% of the people walking through the door said 'I want the right to vote... We can't let Donald Trump, and people like him, get elected.'"
"They are more motivated now," Durazo said. "We have to be there organizationally to convince them to go all the way -- to become a citizen, register to vote and actually vote."
Trump's campaign manager, Corey Lewandowski, argued that there is no empirical data yet to show that Trump cannot improve his standing in the West. And the campaign believes he will do better among African-Americans than many recent GOP nominees.
"We're campaigning in all the states; we're not taking anything off the table," Lewandowski said. "The Obama coalition is a very different coalition than what Hillary Clinton can put together... Barack Obama was significantly younger than Hillary Clinton is -- cooler, hipper. I don't think it's fair to say the coalition that Barack Obama put together is fully behind Hillary Clinton. If that was the case, she would have won more primary elections."
Lewandowski noted that Trump's unfavorability ratings have improved in some polls since he entered the race. "Every assumption the mainstream media has perpetrated" about what Trump can or cannot do "has come out to be absolutely wrong and false."
The fluidity and unpredictability of the race was underscored by a Washington Post-ABC News poll released Sunday. After consistently trailing Clinton in hypothetical general election matchups, the new poll showed Trump and Clinton in a dead heat. It also found that both Clinton and Trump have historically high unfavorable ratings for politicians poised to claim their party's nominations.
Meanwhile, the Quinnipiac University Swing State poll -- which focuses on Florida, Ohio and Pennsylvania because every winner in a presidential cycle over the last five decades has won at least two of those three states -- showed a margin of error race in all three states.
What is beyond dispute is that Trump won the primary by doing exactly the opposite of what the "GOP Growth and Opportunity Project" report commissioned by the Republican National Committee had recommended after Romney's loss in 2012.
The report was commissioned to study why Republicans presidential candidates had lost the popular vote in five out of the last six elections in states they used to win: including New Mexico, Colorado, Nevada, Iowa, Ohio, New Hampshire, Virginia and Florida.
Taking the long view of how the nation's demographic shifts would increasingly work against them with each presidential cycle, party leaders were blunt in the report's assessment that the party had "lost its way with young voters" and "many minorities wrongly think that Republicans do not like them or want them in country."
They were concerned, not just about the Republican decline among Hispanic voters -- from George W. Bush's more than 40% mark to Romney's 27% in 2012 -- but also about the dip among Asian voters. There, too, the shift was stark, from Bush's 44% of the Asian vote in 2004 to Romney's 26% in 2012.
To gauge the long-term impact of Trump's sharp and divisive rhetoric -- and Democrats' efforts to organize against it -- the state to watch most closely is Arizona.
Frey, the Brookings demographer who is the author of "Diversity Explosion," notes that the influence of the white conservative electorate that made Arizona a red state in 15 out of the last 16 presidential elections is being tempered by the growth of the young Hispanic population. By some estimates, minorities could make up 40% of the eligible voters in Arizona this year.
In past elections many of those Hispanic voters have not turned out. In 2012, for example, about 72% of Arizona's voters were white.
That could change this cycle, Frey said, if Democrats pulled off a massive turnout of younger, minority voters to balance out the older, white retirees who typically turn out in droves.
"If you did all of that, then it's possible for Democrats to take Arizona, but it's a huge lift," he said.
Trump begins his western swing this week in New Mexico, a state that underscores his challenge.
New Mexico, which will hold its primary on June 7, was a state that George W. Bush narrowly lost to Al Gore by a stunning 366-vote margin in 2000, but then won in 2004. Obama easily carried New Mexico in 2008 and 2012, placing it in the solid Democratic column in CNN's 2016 battleground map.
Still, Trump's campaign says he intends to compete there this fall.