Sen. Ted Cruz (R-Texas) knows exactly what kind of justice he won't nominate to the Supreme Court if he becomes president: a fake conservative like that wishy washy Chief Justice John Roberts.

Democrats don't consider Roberts in the least bit liberal. He has presided over a court that routinely sides with big business and gave the country the Citizens United decision that loosened campaign finance laws.

But for Cruz, Roberts is no better than former Justice David Souter, whom President George H.W. Bush appointed to the court in the expectation that he'd be conservative. Souter turned out to be moderate and often sided with the court's liberals.

"The virtue of both Souter and Roberts is they didn't have a paper trail," Cruz told the Greenville County Republican Women's Club Thursday. "They were stealth candidates . And frankly, their advisers went and said, 'Wink wink, nudge nudge, they're really secretly conservatives,' but no one can prove it."

"Now let me suggest a principle: If you have lived 50 years of your life, and you've never said, done, or written anything to demonstrate you're a conservative, ya ain't," he added.

But Cruz is on shaky ground with asking conservative audiences to trust his opinion on Supreme Court nominees: He was one of Roberts' biggest defenders when his nomination was before the Senate.

In July 2005, Cruz, who was then Texas solicitor general, wrote an oped for The National Review defending Roberts from detractors who worried about his conservative bonafides:

As an individual, John Roberts is undoubtedly a principled conservative, as is the president who appointed him. He clerked for Chief Justice [William] Rehnquist, worked in the Reagan White House, and served as the principal deputy solicitor general in President George H.W. Bushs Justice Department.

But, as a jurist, Judge Robertss approach will be that of his entire career: carefully, faithfully applying the Constitution and legal precedent.

The Senate should confirm him swiftly.

Cruz also took credit for bringing Roberts into the fold of the George W. Bush campaign, when they needed someone to defend them in Bush v. Gore.

In November of 2000, I had spent the past year and half as domestic-policy adviser on the Bush campaign, and was part of the team assembling the lawyers to help litigate Bush v. Gore. We needed the very best lawyers in the country, and I called John and asked him to help. Within hours, he was on a plane to Florida.

Cruz often goes after Roberts on the campaign trail. In a September debate, he said if Bush had picked someone more conservative for the court, "Obamacare would have been struck down three years ago , and the marriage laws of all 50 states would be on the books."

Cruz has also disavowed his earlier support of Roberts.

"It is true that after George W. Bush nominated John Roberts I supported his confirmation. That was a mistake and I regret that," Cruz said in September.

The issue has new salience in the wake of conservative Justice Antonin Scalia's death. Senate Republicans are promising to block any nominee put forth by President Barack Obama , arguing that the next president should get to make the choice (hoping, of course, that a Republican will win the election).

And the GOP presidential candidates are trying to prove to the Republican base that they would nominate the most conservative Supreme Court justices.

"We are one justice away from the Second Amendment being written out of the constitution altogether," Cruz said Sunday. "And if you vote for Donald Trump in this next election, you are voting for undermining our Second Amendment right to keep and bear arms."

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