Gov. Charlie Baker has until Sunday to decide whether to sign a massive expansion of early and mail-in voting that would alter the way campaigns and elections are run in 2020, but if he waits, he would give Secretary of State William Galvin very little time to comply with a key element of the law.

The legislation sent to Baker's desk on the Thursday before the Fourth of July holiday weekend directs Galvin to mail an application for a mail-in ballot to all 4.5 million registered voters in Massachusetts by July 15.

Baker has said very little about his thoughts on voting-by-mail, often brushing aside questions in the build up to the bill's passage by suggesting there would be plenty of time down the road to consider it. But now with a bill on his desk, he has until July 12 to decide whether to sign, veto or return it with an amendment.

The vote-by-mail legislation (H 4820) is one of three bills currently awaiting action from the governor. Baker has until Thursday to act on a bill (S 2328) to preserve the historic schooner Ernestina-Morrissey in New Bedford, and until Sunday to decide on a bill related to the retirement of a Salem police officer.

Baker's office, when asked about the voting reform bill on Monday, released a generic statement indicating that the governor reviews all bills that reach his desk. He made much quicker work on Thursday of a bill authorizing $200 million in Chapter 90 borrowing for local road and bridge repairs and extending for a year the authority of the MBTA's Fiscal and Management Control Board.

He signed that bill Thursday evening just hours after its enactment, along with five other local bills.