Despite Trump’s polling lead, there are significant obstacles to his running away with the nomination in the coming weeks. With Rubio buoyed by momentum, Nevada’s organizing-heavy caucuses set for Tuesday, and the first half of March weighted toward states where Cruz is poised to finish strongly, there is little space for Trump to translate that lead into a certain nomination in the coming weeks.

“We’re still in February. We’re three states in to this. Trump’s off to a good start but the dynamic of the race is changing after tonight,” said Republican strategist Henry Barbour, a critic of Trump’s.

Meanwhile, Rubio’s strength makes him the standard-bearer of center-right Republicans and their deep-pocketed backers as Jeb Bush’s departure from the race frees resources for the Florida senator and clears out a cluttered field before the real action begins…

“He has a low ceiling that’s going to make it hard for him to close the deal as the field narrows,” said Barbour. “His core vote’s going to stick with him, but I have serious doubts that he can grow it to where he needs to to get to 1,237 delegates.” Trump, for his part, maintains he will pick up a healthy chunk of the supporters freed up as his rivals drop out.