Donald Trump won convincing victories Tuesday in the Michigan and Mississippi primaries, as well as the caucuses in Hawaii, suggesting that the intensified GOP establishment assault on Trump’s character and record had not yet wounded the front-runner for the Republican presidential nomination.

In Michigan and Mississippi, Trump galvanized huge populations of white working-class voters with his populist economic pitch, nativist rhetoric and outsider appeal to win by double-digit margins, further solidifying the billionaire mogul’s lead in the rollicking nomination battle.

Sen. Ted Cruz (R-Tex.) came in second in the Hawaii caucuses. But he won Idaho decisively, followed by Trump in second and trailed by Sen. Marco Rubio (Fla.) and Ohio Gov. John Kasich.

But the night’s marquee event was in Michigan, where late returns showed Kasich and Cruz still competing for second place behind Trump. In Mississippi, Cruz ran a distant second. Finishing far behind in both states was Rubio, who was on track to record some of his poorest results of the season and was in danger of not qualifying for a single delegate in either state, nor in Idaho.

Tuesday’s contests come at a critical juncture for the Republican Party. The runaway front-runner only a couple of weeks ago, Trump was forced onto the defensive over the past week by his own missteps and by a barrage of savage attacks from his rivals and opposing super PACs.