A new Washington Post report says that Jeb Bush's presidential campaign is entering a "make or break" period, claiming that the former Florida governor's top donors are getting antsy about his lackluster poll numbers.

The report states:

The warnings, expressed by numerous senior GOP fund­raisers in recent days, come as Bush and an allied super PAC are in the early stages of an aggressive television ad campaign they say will help erase doubts about his viability.

But Bush continues to battle against a steady decline in the polls, sinking to fifth place at just 7 percent in a national NBC News/Wall Street Journal poll released Sunday and similarly languishing in the early-voting states of Iowa and New Hampshire.

The warnings from top donors come as Wisconsin Gov. Scott Walker’s exit from the race re­focused the battle within the GOP’s establishment wing as one between Bush and his former protege, Sen. Marco Rubio (R-Fla.). Right now, the momentum appears to be behind Rubio, who has jumped ahead of Bush in most polls. At least a third of the bundlers who signed up to raise money for Walker have switched their allegiance to Rubio, while a smaller number have gone with Bush, according to people familiar with the discussions.

In an interview on Fox Business Network this morning, Bush dismissed his sagging poll numbers, and expressed confidence that he will turn it around. 

Bush touted polls that show he can beat Hillary Clinton, saying he believes a governor or former governor should be the party's nominee.

He said his poll numbers will go up once voters start hearing about how he grew the Florida economy for 4% a year for eight years.

On Fox News Sunday, Bush called the race a "marathon" and expressed confidence that he'll win the New Hampshire primary.  

"These polls really don’t matter," he told Chris Wallace.

"They don’t filter out the people that aren’t going to vote. I know it’s an obsession because it kind of frames the debate for people for that week, but I'm in it for the long haul,” he said.

Watch Maria Bartiromo's interview with Bush above.