Two new NBC News/Marist Republican presidential preference polls spell bad news for former Florida Governor Jeb Bush — in just two months, support for his 2016 presidential campaign has plummeted from 12 to 6 percent in Iowa, and from 14 to 8 percent in New Hampshire.

According to a summary of July and September Marist College polls of potential Republican voters in the two earliest contests of the 2016 presidential primary season, Bush and Wisconsin Governor Scott Walker are rapidly losing support. Walker has plunged from 19 to 5 percent in Iowa and from 12 to 4 percent in New Hampshire.

Marist College’s poll summary noted, “Trump has improved his standing among potential Republican voters in both crucial GOP contests. In Iowa, Trump, 29%, leads the crowded GOP field, and retired neurosurgeon Ben Carson, 22%, assumes second place. Dr. Carson is the favorite ‘second choice’ among potential GOP voters. Trump, 28%, also takes the top spot in New Hampshire where he outpaces Ohio Governor John Kasich, 12%, and Dr. Carson, 11%, by double digits among the state’s potential Republican electorate. Carson is also the preferred ‘second choice’ in New Hampshire.”

According to the most recent NBC News/Marist Iowa poll, Kentucky Senator Rand Paul is now tied for fourth place in the state with former Hewlett-Packard CEO Carly Fiorina and Wisconsin Governor Scott Walker.

The September NBC News/Marist polls in both states were conducted over a period of time from August 26 to September 2.

[RELATED: Latest Poll: Sanders Gains Strongest Lead Yet On Clinton In New Hampshire]

Marist College Institute for Public Opinion director Dr. Lee M. Miringoff said, speaking on the results of the organization’s polling on both sides of the aisle, “There’s been a massive shakeup in both parties, in both states. It’s been a summer of surprises with Donald Trump and Bernie Sanders sitting in the front car of the rollercoaster.”

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