Less than a week after delivering a fiery speech condemning Donald Trump and calling on the Republican Party to prepare for a brokered convention, Mitt Romney has begun executing his own plan to deny the G.O.P. front-runner the nomination, dividing the remaining pool of primary state delegates by offering to support not one non-Trump candidate but all of them.

CNN reports the 2012 Republican presidential nominee has made several get-out-the-vote robocall recordings for Marco Rubio and John Kasich that will run in Michigan and Idaho, which both hold their G.O.P. primaries Tuesday. Romney has ties to both states—his father, George Romney, was a popular Michigan governor, and Idaho has a large Mormon population—giving his bigamous strategy some traction. And Romney does not want to keep this a Republican three-way, either. Ted Cruz told reporters that Romney had reached out to him too. “I’ve talked to him on the phone,” he said during a presser, though he did not elaborate on what Romney offered, or whether he would accept. (Cruz, who has been positioning himself as an outsider running against the “Washington cartel,” may be wary of accepting support from a man who so thoroughly embodies the establishment.)

Romney’s anyone-but-Trump endorsement comes days after his speech exhorting the G.O.P. to reject the billionaire showman, even if it means a contested convention in June. That once unorthodox strategy has gained increased acceptance over the past several weeks, as Republican leaders brace themselves for the possibility that Trump could preempt anyone else from reaching the delegate threshold needed to secure the nomination. On Tuesday, New York Times columnist David Brooks published a column making the case for a brokered convention to save the Republican Party, even if it means sacrificing the G.O.P.’s hopes of retaking the White House. “This isn’t about winning the presidency in 2016 anymore,” he writes, urging Republicans to pick an alternative to either “Trumpian nationalism” or the “fading orthodoxy” represented by Cruz.

While a move by the Republican powers that be to override the will of Trump voters would be dramatic, cacophonous, and potentially party-fracturing, it might have some popular appeal. A new national poll indicates that Trump’s support has started to fall, as more G.O.P. candidates have dropped out, shrinking the field to four. Another poll has even worse news for Trump, finding that in a head-to-head confrontation with either Rubio or Cruz, he loses by a not-insignificant margin.

Rubio and Kasich have both indicated that they’d be willing to participate in a brokered convention, with Rubio’s team all but admitting that it could be their only path to victory, and Kasich noting that the convention will be held on his own home turf of Cleveland. Cruz has publicly rejected the idea of a brokered convention, but the longer that Trump remains slightly ahead of him, and the longer that he does not hit the magic number of 1,237 delegates needed for the nomination, Cruz might decide that it’s worth going back on his word, just this once.