Twitter: Scott Walker Presidential Announcement Tweet Wasn't His Fault

UPDATE: A tweet from the Wisconsin governor Friday said he was running for president — three days before his real announcement. Late Friday, Twitter said the tweet wasn't Walker's fault.

On Friday, a photo with the words "Scott Walker Is Running For President" was tweeted from Walker's account.

A Twitter spokesman said Friday night that the tweet wasn't the Walker campaign's fault:

"We're looking into today's issue, and we've determined the Walker team was not at fault," the spokesman said in a statement.

Twitter did not provide further information on what exactly happened.

On Monday, Walker is expected to announce his candidacy, which will be the culmination of a lot of early pre-official campaigning for most of the year.

Since Iowa Freedom Summit this winter, he has aggressively campaigned in early presidential primary states this year and is considered a top Republican contender for the nomination.

The Wisconsin governor is best known for his battles with public unions. After he passed a budget that required public workers to contribute more money to their pension plans and limited collective bargaining in the public sector, unions protested for weeks, and ultimately helped force a recall election in 2013, which Walker won decisively. Because of the recall, the Republican has won three statewide elections in a blue state.

Early on, Walker has focused on his conservative record and pitched himself as a slightly more populist alternative to many of the other prospective candidates.