Congress returns after holiday break to face lengthy to-do list – as it happened

• Lawmakers bid to pass bills on shutdown and assault rifles
• Sign up to receive First Thing - our daily briefing by email

Here's more on Arizona's election controversy, from the Hill.

Maricopa residents can cast a ballot at any of the county's vote centers, so poll workers print customized ballots on demand to match one of more than 12,000 ballot styles, depending on where a voter lives.

But after previously testing the printers, county officials say they began hearing at 6:30 a.m. on Election Day that some machines were printing ballots too light for tabulators to read.

Republican supervisors in Mohave County said last week that they will sign off Monday but wanted to register a protest against voting issues in Maricopa County.

In Cochise County, GOP supervisors demanded that the secretary of state prove vote-counting machines were legally certified before they will approve the election results.