Two bills could be brought up for debate or a vote, though neither is scheduled.
Art Halvorson will face Rep. Shuster in Tuesday's primary.
Rep. Mike Pompeo says he will not challenge Sen. Jerry Moran in a GOP primary.
The Senate will vote on an amendment to the legislation.
The Senate will also consider its first spending bill of the year.
Tuesday's races test if incumbents can win under ethical clouds and the power of self-funding.
Both chambers are preparing legislation to thwart Obama's hope of closing Gitmo
The legislation would allow federal grants for police training programs.
Grassley said Reid has been "crying" over previous holds on nominations.
"His presence inspired and will continue to inspire millions of people," Al Franken said.