President Donald Trump and Senate GOP leaders are desperate for a show of legislative unity on tax reform after the collapse of Obamacare repeal.

But they’re unlikely to get it thanks to Sen. Rand Paul (R-Ky.). The frequent GOP contrarian is digging in against the budget as written — an ominous start to Republicans’ tax push at a time when leaders would like to soothe jittery donors and voters.

Trump and Senate Majority Leader Mitch McConnell have been quietly working to get all Republicans on board with the GOP budget. Unanimity would give the party critical momentum after a brutal few months of intraparty fighting and send a clear message that all 52 members are in play on tax reform.

Sen. John McCain (R-Ariz.), whose defection along with Paul’s helped doom the GOP’s Obamacare repeal bill, was also wavering on the budget until Tuesday. But he’s now willing to fall in line, soothed sufficiently that there will be a future boost in defense spending.