Donald Trump’s campaign is facing new internal discord over who is advising the candidate and whether his current team must expand if he is to make good on his quest for his party’s presidential nomination, sources within the team told NBC News.

The dissent comes at a pivotal moment for a campaign team coming off a significant loss in Wisconsin.

Internal disputes simmered as Trump soared in the polls and outpaced his Republican competitors in primary races. But after several tough weeks, peppered by a charge against Trump’s campaign manager for misdemeanor battery, and then comments from the candidate that infuriated all sides of the abortion debate, some within the Trump team said it was time for changes.

“There are essentially five or six people in the campaign,” said one person who would only speak on the condition of anonymity. “Certain people don’t want to lose power.”

Trump’s inner campaign circle includes campaign manager Corey Lewandowski, communications manager Hope Hicks, deputy campaign manager Michael Glassner and senior advisor Dan Scavino.

Speaking Tuesday with MSNBC, Trump said he had “not heard anything about inner fightings of the campaign. But you know we have a very successful campaign going and I think we're going to keep it going.”

Lewandowski said reports of turmoil were “wholly inaccurate.”

"Mr. Trump is the final arbiter of what goes on in this campaign,” Lewandowski said in a phone interview. “He decides what the messaging is. That will not change regardless of my involvement or anyone else's involvement in the campaign,” he said.

Related: Cruz Win in Wisconsin Loosens Trump's Grip on Nomination

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The candidate has been fiercely loyal to his team, publicly defending Lewandowski who was charged last month with simple battery after a reporter said he grabbed her during a Trump event at a Florida golf course.

Lewandowski and Trump appear to be close, with the candidate staunchly defending and often inviting his manager onstage at rallies and celebrations. But sources close to the candidate said Lewandowski has not been able to deliver tough advice to Trump when he needs it and doesn’t have the authority to demand that he be comprehensively prepared for interviews or public appearances. Consequently, the candidate has appeared at times less than fluid in key policy areas.

Last week, Trump walked back comments about whether women should face punishment for seeking an abortion if the procedure was illegal.

Trump initially told MSNBC’s Chris Matthews that he would support some punitive measure, a comment that drew ire from abortion rights advocates and opponents alike.

Afterwards, one high powered and experienced friend of the campaign confided to NBC News that he told Trump to “lay low” and wait out the news cycle. Instead the campaign continued with interviews and was forced to issue three clarifications on the abortion comments in 72 hours.

While Trump has generally become accustomed to dominating his party’s primary contests, and winning in the polls, the latest incidents have been harder to overcome. A NBC News/Survey Monkey poll out Tuesday showed Trump falling three points nationally though he still leads his main rival, Sen. Ted Cruz of Texas, by double digits.

Related: Meet the Teen Whose Abortion Question Could Sink Trump

There have been previous tensions with the campaign. Last summer, longtime advisor Roger Stone and aide Sam Nunberg were both pushed out of the inner circle by Lewandowski, according to two sources familiar with the power struggle. Lewandowski also succeeded in sidelining Trump's longtime counsel Michael Cohen, the sources said.

Lewandowski spent the next nine months virtually alone at the campaign’s helm, with final approval over everything from strategy, to low-level state hires and media requests. But when it came to the candidate, Lewandowski was hands off early on.

In August, he described the campaign's debate strategy to NBC News as "let Trump be Trump," a phrase that quickly became the campaign’s unofficial motto. The strategy proved successful as Trump continued to rise in the polls and he discarded rivals with relative ease despite missteps.

Despite Tuesday’s loss in Wisconsin, Lewandowski pointed to the campaign’s continued success and noted that his candidate has won 21 of the 33 contests so far.

“If I was running the Cruz campaign and we had won 9 primaries out of 33, I absolutely should be fired but that's not where we are."

Yet, as the election season has matured and Trump has been forced to grapple with a myriad of policy issues, some loyalists noted frustration even from some family members. They questioned whether the campaign team of a half dozen was too small, too inexperienced, and unnecessarily antagonistic to lock up the nomination.

It is unclear to what extent that may be impacting internal change. But the campaign has brought on influential new hires, including experienced operatives such as Barry Bennett and Paul Manafort.

One source with knowledge of the situation tells MSNBC’s Ari Melber that Manafort views his role as a broader authority than what Corey Lewandowski might think. Manafort was said to have conveyed to the campaign that he needs absolute control of strategy for state conventions and a potential floor fight in Cleveland.

While the campaign team is still slim, Lewandowski said Trump’s circle is wider than previously reported. The candidate “frequently and regularly meets with senior elected officials and senior executives we don't brief the press on."

"Mr. Trump just spent an hour and a half with his foreign policy team this week. He spent an hour and half with them last week as well discussing issues of national security matters and foreign policy. Some of the most well-known and respected leaders in the United States, including military officers, think tank experts, and a series of additional policy experts to provide Mr. Trump with the best information available by the experts in their field,"Lewandowski said.

Already the campaign seems to be setting a new course, issuing serious position papers, tailoring expectations in the primary fight and dispatching advisers to state conventions to secure delegates for the July convention in Cleveland.

"It's a natural progression" one source said, adding that "the team is going to expand" and more voices will be brought in as the campaign continues.