Washington - Tensions between the Republican Party and its own front-runner erupted into a full-blown public battle as top party officials rebuked Donald Trump on Friday for alleging that the GOP primary system was "rigged" against him. The dispute, which has been simmering for days, centres on Trump's failure to win any delegates last weekend in Colorado, which selected its 34 delegates at a party convention rather than a primary attended by voters. All went to Trump's chief rival, Senator Ted Cruz of Texas, The Washington Post reported. The outcome prompted a daily stream of complaints and allegations this week from Trump, who wrote in an op-ed published in Friday's Wall Street Journal that the "system is being rigged by party operatives with 'double-agent' delegates who reject the decisions of voters." A senior Republican National Committee official fired back with a thinly veiled response, writing in a Friday memo to reporters that "each process is easy to understand for those willing to learn it." "It ultimately falls on the campaigns to be up to speed on these delegate rules," wrote RNC communications director Sean Spicer. "Campaigns have to know when absentee ballots are due, how long early voting lasts in certain states, or the deadlines for voter registration; the delegate rules are no different." The fight again pits Trump against a Republican establishment that is still broadly opposed to his candidacy and struggling to reconcile with the possibility that he could be the GOP presidential nominee in November. Veterans of past presidential campaigns warned that the feuding could have an adverse effect on down-ballot races and on the ability to defeat Hillary Clinton, seen as the likely Democratic nominee, in the fall. "Traditionally, this is the time that the party and front-runner come together and make the plans necessary to defeat the Democratic candidate in the fall," said Michael Steel, who was an aide for Jeb Bush's campaign and previously worked on the Mitt Romney campaign in 2012 and as spokesman for John A. Boehner (R-Ohio) when he was house speaker. "That's clearly not happening, and it's going to make it tougher to beat Secretary Clinton." One of the keys to Trump's success until now has been his willingness to harshly criticise the party establishment, but he will need the support of the RNC in fundraising and get-out-the-vote efforts if he wins the nomination. This has left Trump boomeranging between fighting the party and trying to embrace it. Early this week, for example, Trump used Twitter and his rally speeches to call the nomination process "corrupt", "rigged" and one that rewards candidates who "play dirty tricks in order to pick up delegates." In an interview with The Hill on Tuesday, Trump said RNC Chairman Reince Priebus "should be ashamed of himself because he knows what’s going on." Priebus responded on Twitter: "Nomination process known for a year + beyond. It’s the responsibility of the campaigns to understand it. Complaints now? Give us all a break." At the same time, Trump's campaign staff was finalising plans to send representatives to the RNC's upcoming spring meeting in Florida and to open an office in Washington. On Wednesday, the real estate mogul had lunch at Trump Tower in Manhattan with Megyn Kelly of Fox News, a longtime target of Trump’s who has come to symbolize his ongoing fight with the party establishment. Later that day, Trump announced he had hired GOP strategist Rick Wiley, who has a long history at the RNC. Thursday night, the journal op-ed under Trump's name went online, reigniting the fires. The fresh tension comes just as the party heads into another busy period of delegate allocation and selection. This weekend, seven states will hold meetings to select at least some of their delegates. Republicans will gather in Georgia, Kansas, Oklahoma, South Carolina and Virginia for meetings in congressional districts to award their delegates. And in Wyoming, Republicans are hosting a convention similar to the one held in Colorado, and Trump's team concedes that they are again poised to lose to Cruz.