Republican presidential candidates, Sen. Marco Rubio, R-Fla., left, Donald Trump, Sen. Ted Cruz, R-Texas,  and Ohio Gov. John Kasich, right,  stand together before the start of the Republican presidential debate sponsored by CNN, Salem Media Group and the Washington Times at the University of Miami,  Thursday, March 10, 2016, in Coral Gables, Fla. (AP Photo/Wilfredo Lee)
Republican presidential candidates, Sen. Marco Rubio, R-Fla., left, Donald Trump, Sen. Ted Cruz, R-Texas, and Ohio Gov. John Kasich, right, stand together before the start of the Republican presidential debate sponsored by CNN, Salem Media Group and the Washington Times at the University of Miami, Thursday, March 10, 2016, in Coral Gables, Fla. (AP Photo/Wilfredo Lee)

The Republican Party’s messy slugfest leading up to this summer’s nomination of a presidential candidate took several unorthodox turns last week, all centered on front-runner Donald Trump, who now calls himself the “presumptive nominee.”

Trump clearly has the upper hand, as the latest Associated Press tally gives him 987 of the 1,237 delegate votes needed to win the nomination. However, his ability to secure the other 250 remains uncertain, and we believe the best-case scenario for the GOP to nominate a credible candidate is an open convention in July.

In an effort to force that, Trump’s remaining active competitors, U.S. Sen Ted Cruz of Texas and Ohio Gov. John Kasich, announced an unusual alliance. Neither now can win enough delegates before the convention to secure the nomination. Their only hope is to block Trump from a first-ballot victory and hope for the best in an open convention.

Cruz now is backed by 562 delegates, and Kasich’s count is 153. However, delegates are bound to a candidate only on the first ballot based on primary voting. After that they could turn to either of the other two, or possibly a compromise candidate such as 2012 nominee Mitt Romney. 

As a first step, Kasich agreed to stop publicly campaigning in Tuesday’s Indiana primary – clearing the way for Cruz to go head-to-head against Trump in a state where the winner takes all 57 delegates. Indiana now is critical to the stop-Trump forces, because a win there would leave him just under 200 delegates short of the magic number.

Cruz, in turn, agreed to step aside in the less critical states of Oregon (May 17, 28 delegates) and New Mexico (June 7, 24 delegates). 

The Cruz-Kasich agreement is limited to those three states and its impact is unknown. Neither candidate is telling supporters who to vote for in the states where they have suspended campaigning; in fact, the day after the pact was announced, Kasich said voters in Indiana still “ought to vote for me.”

At mid-week, Cruz announced that if nominated, his vice presidential choice would be Carly Fiorina, the former GOP candidate who already was actively campaigning for him after dropping out of the race in February. Candidates usually wait until they win the nomination to announce a running mate, and it is unprecedented for a trailing candidate to make the choice public nearly three months before the party convention.

Analysts see several advantages for Cruz: Fiorina, like Trump, comes from a business background; she has political experience in California (where she was the Republican nominee for U.S. senator in 2010), the state with the largest number of delegates (172 on June 7) still to be awarded.

Other more cynical theories about the choice of Fiorina involve her earlier clashes with Trump in which he made dismissive and disparaging remarks about her accomplishments as a businesswoman, as well as her appearance. More of that, those theorists suggest, would further weaken Trump’s support among women and continue to focus attention on whether he has the temperament to be president.

As for Trump himself, he has beefed up his campaign staff with experienced advisers who promised a new, more presidential-acting candidate. Trump rolled that out in his first major foreign policy address Wednesday in Washington, D.C.  

Instead of his usual unscripted, often confrontational remarks at campaign rallies, Trump delivered the 38-minute address with the aid of a teleprompter. While it drew some praise, the speech was mostly panned by politicians and foreign policy experts who criticized everything from Trump’s “America First” slogan (a phrase used by isolationists in the days leading up to World War II) to his lack of specificity and contradictions within the address. We stand by our advice to Massachusetts voters before the March 1 primary when we urged them to reject both Trump and Cruz – two extremists masquerading as populists – in favor of Kasich. While far from a perfect candidate, Kasich remains the most credible choice for the Republican Party because of his more moderate positions and his consensus building. The best course now for the GOP is an open convention which gives Kasich a chance to make that case.