Mitt Romney has topped the 1,144-delegate threshold to be the Republican Party's nominee in the U.S. presidential race, but five of the remaining six primaries are on tap for Tuesday.
Following last week's Texas primary, Romney has 1,183 delegates, followed by now-departed candidates Rick Santorum with 261 and Newt Gingrich with 135. Ron Paul, who now is focusing on state party conventions, has 129 delegates.
The Republican National Committee effectively confirmed Romney's standing, The Miami Herald reported.
"I congratulate Governor Romney on winning the Texas primary and securing the delegates needed to be our party's official nominee at our convention in Tampa," RNC Chairman Reince Priebus said.
Paul's delegate count will grow as more state parties convene to officially elect delegates to the Republican convention in August in the Florida city.
On Wednesday, President Obama called Romney to congratulate him, The Washington Post reported.
"President Obama said that he looked forward to an important and healthy debate about America's future, and wished Governor Romney and his family well throughout the upcoming campaign," the White House said in a statement.
California, Montana, New Jersey, New Mexico and South Dakota conduct their primaries Tuesday.
California has 172 delegates in a winner-takes-all contest. New Jersey has 50 delegates and also runs a winner-take-all primary.
Montana has 26 delegates in a non-binding primary.
New Mexico has 23 delegates in a proportional primary.
South Dakota's primary also is proportional. The state has 23 delegates.
National Public Radio asked several political analysts which presidential election the 2012 tilt most resembles -- and got several different answers.
Alison Dagnes, a political science instructor at Shippensburg University, told NPR the 2012 race hearkened back to the 1936 contest between Franklin Delano Roosevelt and Alf Landon.
"The Republicans tried to attack FDR for his New Deal programs, saying they were too expensive and moved the country toward socialism -- sound familiar?" Dagnes asked.
The problem with that argument, she said, is that people are loathe to give up their rights -- such as ones granted in Obama's signature healthcare reform bill -- once they get them.
"The [Obama] campaign is gambling on this FDR-style move of giving more to the public, who will want to keep it," she said. "Same goes for the rest of the social programs Obama is touting today -- it's expensive, all right, but who doesn't want a better educated public? Et cetera."
Andrew Smith, director of the University of New Hampshire Survey Center, said he found similarities with the 1980 contest between Jimmy Carter and Ronald Reagan.
"Young, unknown president is elected after an unpopular administration … economy in the doldrums, problems with Iran, sense of malaise," Smith told NPR. "Republicans nominate the person who finished second place in the previous nomination … after a divisive nomination struggle. But the GOP came together in 1980 and are coming together in 2012, while the economy continues to drag at the incumbent."
Emory University political science professor Alan Abramowitz said he sees similarities with the 2004 George W. Bush-John Kerry match-up.
"This year, just as in 2004, you have an incumbent president running for re-election in a polarized and closely divided electorate," he told NPR.