But Twitter later said the tweet was a mistake on their part, not the Walker campaign's.
The account of the Wisconsin governor, who will announce his intentions on Monday at an event in the Badger State, tweeted an image Friday that read "Scott Walker is running for president" and asked followers to "join the team."
That tweet has since been deleted from his Twitter timeline, but it was still live
as of early Friday evening.
Kirsten Kukowski, a spokeswoman for the campaign, tweeted Friday that people should "stay tuned" for the governor's announcement on Monday.
But late Friday, Nu Wexler, a Twitter spokesperson, said "We're looking into today's issue, and we've determined the Walker team was not at fault." It was unclear how the error occurred.
Walker campaign spokeswoman AshLee Strong declined to elaborate beyond Twitter's statement on Saturday morning.
Walker has used a political committee called Our American Revival to hire a large political staff and travel the country. Officially, Walker was merely considering a presidential run as he finished up a legislative session in Madison, but the governor has been widely expected to run for president for nearly all of 2015. Walker will sign his state's budget in Waukesha on Sunday after a protracted battle in Madison.
Walker currently leads nearly every poll in Iowa, which will host the first caucuses next winter.
There are so far 14 official Republican presidential candidates, with Walker and Ohio Gov. John Kasich expected to announce their candidacies later this month, and former Virginia Gov. Jim Gilmore slated to officially announce his bid next month