The Ted Cruz and John Kasich campaigns announced apparent coordinated strategies to combat Donald Trump in select upcoming primaries — an effort to force an open convention when the Republican National Committee gathers in Cleveland in July.

In a statement sent out Sunday evening, the Cruz campaign said it will focus resources on Indiana, "and in turn clear the path for Gov. Kasich to compete in Oregon and New Mexico."

Kasich's camp offered an inverse statement within minutes, saying it will "give the Cruz campaign a clear path in Indiana" while focusing on New Mexico and Oregon.

Both campaigns called on their allies and third-party groups to cooperate with this approach.

Trump responded late Sunday on Twitter:

"Wow, just announced that Lyin' Ted and Kasich are going to collude in order to keep me from getting the Republican nomination. DESPERATION!"

In another tweet, he said:

"Lyin' Ted and Kasich are mathematically dead and totally desperate. Their donors & special interest groups are not happy with them. Sad!"

Indiana's primary is on May 3. Oregon votes on May 17. New Mexico is one of the states on the final day of the GOP primary calendar, June 7.

Both the Kasich and Cruz camps say they will compete to win other contests in the Republican race over the next six weeks — including the five states voting on Tuesday (Pennsylvania, Delaware, Maryland, Connecticut and Rhode Island) or other states down the line, including Nebraska, West Virginia, Washington, California, Montana, New Jersey, North Dakota and South Dakota.

At this point, Kasich is mathematically eliminated from earning the 1,237 delegates needed to win the GOP nomination outright. Cruz is likely to also be mathematically eliminated if he does as poorly as polls are suggesting on Tuesday. A contested convention has become their only possible path to stop Trump from being the nominee.

(NPR)