Many of the Wall Street financiers who have been mainstays of Republican “super PACs” in the six years since the Supreme Court’s Citizens United decision have rallied behind Senator Marco Rubio of Florida, betting that he is the party’s best chance to win a general election battle against Hillary Clinton…

But the steady rise of Senator Ted Cruz of Texas, a Tea Party favorite reviled by party leaders, has unleashed a new counter-establishment of conservative donors, some from outside the universe of traditional Republican giving. They include wealthy evangelicals, libertarian businessmen, Israel hawks and others disenchanted by the party’s past nominees, and are drawn to Mr. Cruz’s uncompromising social conservatism and his promise to disrupt the party’s traditional power brokers in Washington…

The expensive five-way shootout is a sharp departure from 2012, when virtually of the Republican donors inclined to write seven-figure checks rallied behind a single candidate, Mitt Romney. And it presents a stark contrast to the Democratic contest, where the biggest checks raised by outside groups have all gone to Priorities USA, a super PAC backing Mrs. Clinton. Priorities reported that it had raised $51 million since the beginning of last year, including a $6 million contribution in December from the liberal hedge fund billionaire George Soros. The biggest outside group supporting Senator Bernie Sanders of Vermont is funded entirely by a nurses union, pooling small contributions from members.