Thanks to Wikileaks, we know that the Democrats wanted to ensure that the Republicans would nominate someone more extreme. Look at the PDF attachment here. There's more than just this quote, too:

Operationalizing the Strategy Pied Piper Candidates

There are two ways to approach the strategies mentioned above. The first is to use the field as a whole to inflict damage on itself similar to what happened to Mitt Romney in 2012. The variety of candidates is a positive here, and many of the lesser known can serve as a cudgel to move the more established candidates further to the right. In this scenario, we don’t want to marginalize the more extreme candidates, but make them more “Pied Piper” candidates who actually represent the mainstream of the Republican Party. Pied Piper candidates include, but aren’t limited to:

• Ted Cruz

• Donald Trump

• Ben Carson

https://wikileaks.org/podesta-emails/emailid/1120 (Read the PDF attached)

Is there anyone else that could have secured a majority in the House and potentially (as of 1247am EST) the Senate? I doubt that, DC politics is more about trading wins like potheads passing the joint around. I don't mean that pejoratively but literally -- Republicans and Democrats trade wins and losses to curry favor with one-another, meanwhile the interests of the American people are secondary to this political snobbery.

Furthermore, who else could have rallied the masses to vote so thoroughly? A Jeb vs Hillary election would have been very dull, almost depressingly so, meanwhile a Cruz vs Hillary election would have bordered on hopelessly disinteresting.