(CNN) A super PAC initially linked to Ted Cruz transformed itself Wednesday into a new big-money group backing Donald Trump, the latest twist in the confusing orbit of pro-Trump super PACs.

The new group, Make America Number I, was until Wednesday known as Keep the Promise I, a group funded almost entirely by $13.5 million from Republican megadonor Robert Mercer. The super PAC will now focus primarily on advertising opposing HIllary Clinton as opposed to supporting Trump, according to spokeswoman Kristina Hernandez, a decision made to give Trump-skeptical donors more comfort in contributing.

Make America Number I is at least the fifth pro-Trump super PAC jockeying to support the Republican nominee. The group will be run by David Bossie, the president of Citizens United and a longtime player in conservative money circles, Hernandez said, giving the organization some credibility as it competes with other groups for checks.

Mercer's PAC only had about $1.3 million on hand as of May 31, but the hedge fund family would reinvest in the new group and that they would actively fundraise, unlike Keep the Promise. Bloomberg Politics, which first reported on the super PAC , said the Mercers were encouraged by Trump's daughter Ivanka to start the organization and that it would be effectively "blessed" as an authorized super PAC.

Mercer has been one of the largest donors in Republican politics in recent cycles, and he had not yet committed to financially backing Trump before the super PAC formed.

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