Story highlights RNC Chair Reince Priebus introduced Donald Trump at a Pennsylvania rally

Reports of tension between the Trump campaign and RNC have emerged of late

(CNN) Republican National Committee Chair Reince Priebus introduced Donald Trump at a Friday afternoon rally, a show of unity with the GOP nominee as he struggles in the polls.

Priebus talked up his party's nominee and slammed Democratic rival Hillary Clinton.

"We're in a battle for freedom in this country. Donald Trump is going to help protect our country," Priebus told a boisterous Erie, Pennsylvania crowd. "Look at the choice we've got. Hillary Clinton has a problem with lying. She lied. She lied. And she lied over and over and over again."

Such appearances by a party chair are not unusual in a presidential campaign, but this one stands out in an election cycle with Trump lagging behind Clinton in a swath of polls, particularly in key electoral states. That's led to tension between the Trump campaign and RNC officials over strategies and tactics.

Priebus spoke to Trump about the direction of his campaign and his impact on down-ballot races, sources told CNN on Thursday. The two are already in regular contact and this particular conversation was described to CNN as not confrontational -- as a Time Magazine piece suggested Thursday -- but rather as a broad overview of the state of the race and the ramifications of Trump's freewheeling style.

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