Because Democrats could do that by a simple-majority vote, Cruz has protested the bill all night in remarks that have exceeded 18 hours as of this post. Cruz started at 2:41 p.m. Tuesday afternoon, and has been standing since then, and talking with the help of other Senate Republicans.

It's unclear when the Senate will try to start its day. Typically the Senate would return at 9:30 a.m. or 10 a.m., but that could be thrown off if Cruz is still talking then.

There were some signs Cruz would try to keep talking right up until the vote happens, which could force Democrats to cut him off to set up the vote.

On the other side of the Capitol, the House returns to work, but it has a light schedule. Members will start at noon, and later in the afternoon, they will consider up to four suspension bills.

One of these is the un-numbered H.Res __, which would allow the House to accept a Senate-passed bill requiring the government to auction off its helium reserves.

The House passed a similar bill this year, H.R. 527. That bill required helium auctions in order to help boost the price of helium, with the hope of creating an incentive for companies to stop relying on government supplies and develop their own.

The Senate bill is similar, although it also includes language extending the Secure Rural Schools Program, which gives federal money to rural areas that are hurt by environmental laws that limit timber harvests and reduce local revenues.

The House has passed similar legislation approving the rural schools program and, thus, is prepared to approve the Senate's addition.

The three other suspension bills up in the House today are:

— H.R. 1961, extending an exemption from the fire-retardant materials construction requirement for certain vessels,

— H.R. 3095, ensuring that new government requirements for testing people operating commercial motor vehicles for sleep disorders are adopted after a formal rule-making process, and

— H.R. 2600, amending the Interstate Land Sales Full Disclosure Act to clarify how the law applies to condominiums.