Story highlights Republican front-runner Donald Trump is expected to rule out a third-party bid Thursday

Trump will have a 2 p.m. news conference at Trump Towers following the meeting with RNC head Reince Priebus

Washington (CNN) Republican front-runner Donald Trump is expected to rule out a third-party bid for president Thursday, following a meeting with Republican National Committee Chairman Reince Priebus in the afternoon.

In recent days, the RNC has circulated a pledge to GOP presidential candidates asking them for their party loyalty and affirm they will not run for president as an independent -- a move many seem aimed at Trump.

The plan is for Trump sign the pledge, sources have said, but much is riding on how well the Trump-Priebus 1:30 p.m. meeting goes.

A separate source from inside the Trump campaign told CNN Thursday that the overwhelming number of calls from supporters have been against taking the pledge.

Trump will have a 2 p.m. news conference at Trump Towers following the meeting with Priebus.

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