House Democrats have come out on both sides of the reclassification issue in recent communications to Wheeler.
More than 100 technology companies, including Google and Facebook, have spoken out against allowing pay-for-priority, although have not called for reclassification.
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Wheeler's proposal reaches the tentative conclusion that some pay-for-priority deals may be allowed, but asks whether the FCC should presume "some or all" such deals are illegal, according to an FCC official briefed on the proposal. It also asks whether the FCC should instead consider reclassification or other net neutrality proposals.
The two Republican FCC commissioners are expected to vote against Wheeler's proposal. Wheeler's two fellow Democrats have both expressed misgivings about the plan, but are likely to vote to launch the process and open it up to public comment.
Read MoreFCC, in 'net neutrality' turnaround, plans to allow fast lane
The FCC will also vote on Thursday on rules for the sale of highly valuable low-frequency airwaves to wireless carriers. Those rules are expected to restrict how much the largest two providers, Verizon and AT&T, can buy.