Marco Rubio is taking steps to ensure that any national convention delegates bound to him remain on his side of the ledger at the outset of Republican National Convention, a move designed to hamstring Donald Trump's attempt to clinch the GOP presidential nomination.

"The decision to suspend my campaign for president of the Untied States is not intended to release any national convention delegates bound to me as a result of the 2016 delegate selection process that took place in your state," Rubio wrote to the Alaska Republican Party in a letter that was also obtained by the Washington Examiner. "It is my desire at this time that the delegates allocated to me by your rules remain bound to vote for me on at least the first nominating ballot at the national convention."

Rubio admitted defeat in the presidential primary fight after losing his home state of Florida on March 15, but the disposition of his delegates could still have a major influence on the outcome of the race. Cruz and Gov. John Kasich, R-Ohio, are working force a contested convention by preventing Trump from garnering the 1,237 delegates needed to win the nomination on the first ballot.

Rubio is happy to help in that effort. "Of course, he's no longer a candidate and wants to give voters a chance to stop Trump," Rubio spokesman Alex Burgos said in an email to the Washington Examiner.

Rubio won 167 delegates as a presidential candidate, and dozens of them will be required to back him on the first ballot of the Republican National Convention, though the rules vary state-by-state. By working to retain his delegates, Rubio is shrinking the pool of "free agents" who could help Trump clinch the nomination on the first ballot.

If Trump fails to win a majority on the first ballot, then he's liable to suffer the most defections of any candidate when delegates vote on successive ballots.

If Rubio had not lodged the request, then Trump and Cruz would have received an equal number of delegates in Alaska. Instead, the state party's apportionment rules meant that Trump lost three delegates and Cruz lost two, which gave the Texas senator a 13-12 lead among Alaska delegates.

Alaska GOP chairman Peter Goldberg approved Rubio's request after receiving the letter on Monday and consulting with RNC lawyers, a state party spokesman who noted they showed Mitt Romney a similar courtesy in 2008. "We treated the Marco Rubio campaign in the same manner we treated all other campaigns that suspended," Goldberg said in a Monday statement.