Paul Manafort, chairman of presumptive GOP nominee Donald Trump's campaign, denied that the campaign is falling behind likely Democratic rival Hillary Clinton's and said "major announcements" will be made this week about national and state-level leadership changes.

The Trump campaign has struggled to reset for the general election amid internal feuding. A Federal Election Commission report last week also revealed that his fundraising lagged behind Clinton's considerably. But appearing on NBC's "Meet the Press" on Sunday, Manafort insisted that the Trump campaign has been organizing behind the scenes for several weeks.

"Our campaign is organized. We're ready. We're going to have a good convention, and we're confident that we are not behind the Clinton campaign," Manafort said. "They're musclebound. We're not."

Manafort said the campaign has operations in key battleground states and has plans and budgets in place. The campaign is now integrated with the Republican National Committee, he said, and plans to make announcements about "major positions" this week.

When asked about last week's firing of embattled campaign manager Corey Lewandowski, whom he replaced, Manafort said Lewandowski "was a part of a historic campaign, and Donald Trump recognizes that. But the campaign has transitioned to a new phase. We're now in the general-election mode of the campaign."