WASHINGTON (AP) The crowds are psyched . The campaign donations are flooding in . Volunteers are showing up at field offices in droves.

After a mostly smooth two-week campaign startup, Vice President Kamala Harris is headed into a crucial week that includes her most critical decision yet choosing a running mate while grappling with how to keep that early political momentum alive.

Harris, a former prosecutor known for being deliberative, effectively has a deadline of Tuesday to select who will be her No. 2 from a list that has been whittled down to four governors, a senator and a Cabinet official who was also one of her 2020 foes. Its a high-pressure decision that usually spans several months, but in this case is compressed into a matter of just weeks.

From there, Harris and her running mate will launch into an aggressive, seven-state battleground tour that begins in Philadelphia on Tuesday and winds through Wisconsin, Michigan, North Carolina, Georgia, Arizona and Nevada. Her early rallies have attracted enthusiastic thousands.

Campaign officials are aware that momentum can be fleeting and are working to capitalize on the energy now, while managing expectations by continuing to emphasize the race with Republican nominee Donald Trump is tight. But the strong rollout has allowed the Harris campaign to put a number of states back in play that had been feared out of reach when President Joe Biden remained at the top of the ticket .

Harris faces new tests in the coming days as she works though key decisions including her vice presidential pick, with the potential to disappoint elements of the coalition.

She has not faced the level of scrutiny that presidential candidates typically face. While she has kept up a busy schedule of public appearances, she has rarely taken questions from the press and has not sat for an in-depth interview. After four years advocating for Bidens positions, shell have to stake out positions of her own on the political controversies that divide Democrats .

Harris message is coming into clearer focus with each day. Her first television ad last week portrayed her as fearless and emphasized what has emerged as a rallying cry for her campaign: We are not going back.

She is also repeatedly emphasizing the concept of freedom, focusing not just on Trump as a threat to democracy but also the freedom to have an abortion and be safe from gun violence.

Meanwhile, her prosecutorial background is emerging as a central dividing line with Trump. In rallies and ads, she contrasts her record going after hardened criminals and corporate wrongdoers against Trumps indictments, convictions and civil judgments.

Trump, for his part, is racing to define her as a soft-on-crime San Francisco liberal who was tasked with securing the border as vice president but failed. He blames her and Biden alike for inflation during their tenure. Hes also gone after her personally, questioning her intelligence and her biracial identity.