Republicans in several states met over the weekend to choose delegates to the Republican National Convention. And the meetings exposed several more problems for GOP presidential front-runner Donald Trump.

The businessman still holds a commanding lead, but will need to dominate the remaining contests to secure the 1,237 delegates needed to win the Republican nomination. Over the weekend, he was unable to win delegate slots in parts of the country that he previously won. He also lost several chances to ensure that supporters earned seats on key committees that will oversee the convention.

Clearly angered by the results, Trump attacked his main opponent, Sen. Ted Cruz (Tex.), on Sunday, saying that his campaign is "trying to subvert the movement. They can’t do it with bodies, so they’re trying to subvert the movement with crooked shenanigans."

Unimpressed, the Cruz campaign crowed.

"It's no surprise that Trump's team will lash out with falsehoods to distract from their failure, as they have the entire time," Cruz spokeswoman Alice Stewart said. "We have earned our success by working hard to build a superior organization and are working within the process and rules that have been established."

Each of the 56 states and territories are assigned different numbers of delegates by the Republican National Committee and use varying rules to pick their delegates. (One uniform rule: Each congressional district gets three delegates.) At the national convention, most delegates will pledge to vote for a certain candidate depending on the results of a state caucus or primary. But the rules vary on what delegates can do in subsequent rounds of voting. That's when a delegate's personal preference will matter -- and that's why the Trump campaign should be nervous about the weekend results.

Need proof? Here's a look at some of what transpired:

ALABAMA: 50 delegates

The Cotton State was a bright spot for Trump. He won the March GOP primary and 36 of the state's delegates.

On Saturday, party leaders choose their eight delegates to serve on the national convention committees that oversee convention rules, credentials for delegates, settle any rules disputes and write the official GOP platform. Trump senior campaign aides Paul Manafort and Edward Brookover said that they won a majority of the committee assignments. But a state party official didn't respond to a Washington Post inquiry about Saturday's results.

Alabama Republicans also selected Sen. Jeff Sessions, a Trump supporter, as their delegation chairman.

COLORADO: 37 delegates

The Cruz campaign completely dominated, winning all of the 34 delegates up for grabs Saturday. (The three remaining delegates are state party officials who can vote however they want in Cleveland.)

Colorado is one of six states or territories that don't use a caucus or primary to elect a president. Instead, Republicans used a series of meetings to dole out delegates and repeatedly exposed the Trump campaign as ill-prepared.

At the state GOP convention, Trump supporters distributed glossy fliers urging people to vote for a slate of their preferred candidates. But several names were misspelled or assigned the wrong ballot number.

Trump's advisers accused Colorado GOP leaders of tweaking ballots in the final hours before the vote, causing widespread confusion. The state party's Twitter account also sent out a decidedly anti-Trump message -- an unauthorized tweet that party leaders said they are investigating.

INDIANA: 57 delegates

The Hoosier State GOP uses one of the most exclusive, closed delegate selection methods in the nation. It appears to have cost Trump dearly.

The party chooses the people who will serve as delegates before the state's May 3 primary. Party leaders in each congressional district present a list of names they want to serve to state party leaders, who choose the delegates in private. The process will conclude Wednesday when party leaders choose the final 30 delegates -- behind closed doors.

A state party spokeswoman hasn't responded to requests from The Post for the names of the delegates chosen so far. But news reports say that party leaders picked delegates who are less likely to support Trump in later ballots at the national convention. With few connections to state party leaders, the Trump campaign concedes it dropped the ball in Indiana.

In Cleveland, Indiana's delegates assigned by congressional district will be required to vote for the winner of their district on the first ballot. The same goes for the state's 30 at-large delegates. After that, they can do what they want.

IOWA: 30 delegates

Republicans in the Hawkeye State's four congressional districts met Saturday to choose delegates, and Cruz won 11 of the 12 seats up for grabs.

Cruz's victory was especially sweet because Trump supporters made a last-minute attempt to wrestle away a few slots.

Delegates supporting Cruz also won five of the state's eight convention committee assignments -- ensuring the senator a stronger voice in those critical organizational meetings.

On Saturday, the Cruz campaign sent text messages to supporters urging them to vote for delegates supporting Cruz, according to local news reports. Supporters for Trump and Ohio Gov. John Kasich showed up at the proceedings but in most cases didn't put up candidates to run for delegate.

Ultimately, nine of the Cruz campaign's 12 preferred candidates won delegate slots. Two others weren't on the campaign's official slate but said they plan to vote for the senator, according to local reports. The final delegate, Mariannette Miller-Meeks, is a former aide to Gov. Terry Brandstad and declined to say whom she would support. That probably means she'll face intense lobbying by the three presidential campaigns.

MICHIGAN: 59 delegates

When Republicans gathered to finalize their delegate slate Saturday, the final results weren't in doubt: Trump, who easily won the state last month, earned 25 delegates, while Cruz and Kasich earned 17 delegates each.

Trump delegates won five of the state's convention committee slots and Kasich delegates won three seats -- a small but important victory for the Ohio governor, who is badly trailing nationwide.

Burned by the loss, the Cruz campaign accused the Trump and Kasich teams of forming an alliance to block the senator. Kasich and Trump supporters didn't deny the charges.

Scott Hagerstrom, a Trump campaign aide responsible for Michigan, said that "it just sounds like people crying over spilled milk. We won the state. We won the vote."

NEVADA: 30 delegates

Trump won the GOP caucus in February -- and there were signs of encouragement for him here Saturday.

The Silver State won't officially assign its 30 convention delegates until May 14, but Trump will get 14 delegates. The party will assign seven delegates to Sen. Marco Rubio (Fla.) (the second-place finisher, even though he dropped out); six to Cruz; two to retired neurosurgeon Ben Carson (another dropout); and one to Kasich.

On Saturday at the Rio Hotel in Las Vegas, the Clark County Republican Party drew thousands of people to figure out who will be going to Reno for the final delegate vote. The county voted to send at least 1,209 people to the state GOP convention and most are Trump supporters, according to the Trump campaign. The Cruz campaign warned it will protest the results.

Team Trump hopes that what happened in Las Vegas will ultimately pay off in Cleveland.

SOUTH CAROLINA: 50 delegates

All of the Palmetto State's delegates are bound to Trump on the first ballot -- but can vote however they want in later rounds.

In the 3rd Congressional District, Republicans on Saturday chose State Rep. Mark Willis and Elliott Kelley, who said they would vote for Cruz in later rounds; and Susan Aiken, who said she remains unpledged after previously supporting Rubio's campaign.

In the 7th Congressional District, Republicans elected State Rep. Alan Clemmons, Charlotte Hendrix and Jerry Rovner as delegates. Clemmons is uncommitted, Hendrix is backing Cruz and Rovner is for Trump.

Those personal preferences won't matter until later rounds -- and signal that Trump will quickly lose South Carolina support in later rounds of voting.

VIRGINIA: 49 delegates

The commonwealth's 11 congressional districts are assigning their delegates ahead of the April 30 state convention.

On Saturday, the 9th Congressional District chose two delegates -- Kyle Kilgore and Jordan Labiosa -- who would support Cruz in later rounds. Tucker Davis, a Trump supporter, won the third slot.

Trump won Virginia's southernmost congressional district overwhelmingly on March 1, so his inability to win all of its delegates is further evidence of poor planning.

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U.S. Republican presidential nominee Donald Trump speaks at a campaign event at Trump Doral golf course in Miami, Florida, U.S. July 27, 2016. REUTERS/Carlo Allegri (Carlo Allegri/Reuters)