Trump slams Cruz-Kasich alliance as desperate and 'sad'
The Economist Intelligence Unit ranked victory for Republican presidential candidate Donald Trump at 12 on an index where the current top threat is a Chinese economic "hard landing" rated 20 (AFP Photo/Jim Watson)

Donald Trump responded to the new Ted Cruz-John Kasich alliance in the same way he responds to everything -- with a series of insulting tweets punctuated with a single-word summation.

Trump's remaining Republican rivals announced the agreement Sunday to allow one another to focus on specific state primaries in hopes of blocking the frontrunner from gaining the GOP nomination.

Trump posted a pair of tweets hours later slamming the move as "sad" and made in "desperation."

The real estate developer and reality TV star has continued to pad his delegate count after winning the New York primary last week, but Kasich and Cruz hope to stop Trump from reaching the required 1,237 delegates he needs to win the nomination.

That would force a contested convention, which could allow another candidate -- possibly one who's not even running -- could become the Republican presidential nominee.

Many delegates would be permitted to back another candidate if none of them has enough support by the first vote at July's Republican National Convention in Cleveland.