Craig, Colorado:
Mitt Romney is poised to clinch the Republican presidential nomination after Tuesday's Texas primary, a largely uncontested election that will formalise the former Massachusetts governor's status as President Barack Obama's general election challenger.
While Mr Romney's nomination has been virtually assured for a month, the day marks the culmination of several years of work, dating back to his unsuccessful 2008 presidential bid, and perhaps far earlier.
"It'll be a big day tomorrow," Mr Romney told reporters aboard his campaign plane on Monday evening. "I'm looking forward to the good news."
But Mr Romney's focus on Tuesday will be hundreds of miles (kilometers) north of Texas, where he's scheduled to court voters and donors in Colorado and Nevada during a two-state swing punctuated by a Las Vegas fundraiser with celebrity real estate mogul Donald Trump.
The evening event, set for the Trump International Hotel, comes amid fresh criticism from Republicans and Democrats over Mr Trump's continued questioning of President Obama's citizenship. Mr Romney hasn't condemned Mr Trump's false claims, offering a fresh example of the presidential contender's reluctance to confront his party's more extreme elements. There have been other examples in recent weeks that underscore Mr Romney's delicate push to win over skeptical conservatives while appealing to moderates and independents who generally deliver general election victories.
Asked on Monday to weigh in on Mr Trump's support for the so-called birther movement, Mr Romney declined to condemn Mr Trump's latest suggestion that Obama was born in Kenya.
"I don't agree with all the people who support me. And my guess is they don't all agree with everything I believe in," Mr Romney told reporters on his chartered plane before flying from California to Colorado. "But I need to get 50.1 percent or more. And I'm appreciative to have the help of a lot of good people."
Polling suggests that the election between Mr Romney and President Obama will be very close, ultimately decided by several swing states, Colorado and Nevada among them. Mr Romney will begin campaigning on Tuesday in the northern Colorado town of Craig before flying to Las Vegas for an afternoon rally before the Trump fundraiser.
The Texas primary offers 152 delegates; Mr Romney is just 58 delegates shy of the 1,144 needed to become the nominee. His Republican rivals Rick Santorum and Newt Gingrich already have endorsed Mr Romney, while libertarian-leaning Texas Rep. Ron Paul has stopped actively campaigning. Mr Gingrich is expected to attend the Trump fundraiser.
But Mr Romney's meeting with Mr Trump may generate as much interest, or more, than his new grasp on the Republican nomination.
"I do not understand the cost benefit here," conservative commentator George Will said over the weekend. "The cost of appearing with this bloviating ignoramus is obvious, it seems to me."
Mr Trump revived the false claims about Obama's birthplace late last week, citing a discredited story about a literary agency that mistakenly listed that Obama was born in Kenya.
Mr Romney has been criticized on several occasions for failing to speak out against extreme rhetoric from his party. The reluctance stands in contrast to the 2008 Republican presidential nominee and current Romney supporter, Sen. John McCain, who once corrected a supporter who called Obama a Muslim.
On Monday, Mr McCain appeared with Mr Romney in San Diego in what was billed as a Memorial Day service paying tribute to the nation's war dead, not a campaign rally. Mr McCain, a Vietnam veteran who spent more than five years as a prisoner of war, said he believes that Romne "is fully qualified to be commander in chief."
Without naming his general election rival, Mr Romney drew clear contrasts with President Obama on the issue of defense.
The Democratic president has proposed reducing the size of the military following the end of the US combat role in Iraq and plans to remove troops from Afghanistan by the end of 2014.
"We have two courses we can follow: One is to follow in the pathway of Europe, to shrink our military smaller and smaller to pay for our social needs," Mr Romney said outside the Veterans Memorial Center and Museum. "The other is to commit to preserve America as the strongest military in the world, second to none, with no comparable power anywhere in the world."
The White House and congressional Republicans have agreed to cut $487 billion in military spending over the next decade. Even with Obama's proposed cuts in the military budget, the U.S. would remain by far the world's dominant military power. The Pentagon's budget this year exceeds $600 billion. Closest rival China said this year its defense budget will top $100 billion for the first time, although the US claims China spends twice as much.
Across the country in Washington, President Obama marked the solemn holiday with remembrances at Arlington National Cemetery, and later at the Vietnam War Memorial marking the 50th anniversary of U.S. involvement in Vietnam.
He noted that for the first time in nine years "Americans are not fighting and dying in Iraq," and the nation was winding down its role in the conflict in Afghanistan.
"After a decade under the dark cloud of war, we can see the light of the new day on the horizon," President Obama said to an audience gathered at the Arlington amphitheater.
The candidates' comments underscored the political and practical effects the presidential contest could have on America's role in the world.