Washington (CNN) Donald Trump accused former rival Jeb Bush of leading an effort among Republican delegates to block him from securing the nomination in Cleveland next month.

"By the way, Jeb is working on the movement, just so you understand. I love competition like that. I love it," Trump said Saturday during a campaign rally in Las Vegas.

A former campaign spokeswoman for Bush, Kristy Campbell, quickly fired back Saturday, calling Trump's "obsession" with Bush "unhealthy."

"Donald Trump's unending obsession with @JebBush is really unhealthy," Campbell wrote.

Donald Trump's unending obsession with @JebBush is really unhealthy.

https://t.co/GbnSZ6gMti — Kristy Campbell (@kristymcampbell) June 18, 2016

Campbell referred CNN to her tweet when asked for comment on Trump's assertion.

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