Ted Cruz

WASHINGTON — Republican leaders Sunday grappled with the prospect the best hope for stopping Donald Trump's march to the nomination may be Ted Cruz — the only candidate who causes as much heartburn among party elites as the billionaire businessman, if not sometimes more.

The Texas senator split contests with Trump in Saturday's voting, bolstering his argument that only he can defeat the real estate mogul. Trump and Cruz are now significantly outpacing Marco Rubio in the delegate count, further shrinking the Florida senator's already narrow path to the nomination.

If Rubio's slide continues, he would be the latest establishment candidate to fall victim to an angry, frustrated electorate that cares little about endorsements from party leaders or newspaper editorial boards. Rubio has rolled out both at warp speed in recent weeks, but his appeal with Republican voters is not keeping pace.

Rubio rejected the idea anti-Trump Republicans should rally around Cruz, arguing the likely scenario is a long fight that leaves the party without a presumed nominee heading into the July convention.

“To be fair, it's hard to imagine at this moment the way things are going anybody getting to” a majority of 1,237 delegates, Rubio said. “Even Trump, he'd have to win over half the remaining delegates to get there and he's not on pace to that now. We'll see what happens.”