Unlike Trump’s very public show of picking his running mate, Hillary Clinton has conducted her search with the utmost secrecy. Clinton has no shortage of candidates who would love to run with her, and her biggest challenge will be not offending those not selected.

Virginia Senator Tim Kaine continues to lead the list as the front-runner. Sen Kaine would be a safe pick, and Hillary has little need to be anything but safe at this point. Kaine brings a solid record of government service and is well suited for the primary role of the vice president, which is to be a heartbeat away if necessary. Kaine, who is 58, would bring a touch of youth to the campaign, just as the 57-year-old Pence will do for Trump.

Others said to be still in consideration are Tom Vilsack, the current Secretary of Agriculture, Sen. Cory Booker, and Sen. Elisabeth Warren. While all three would bring some strengths to the ticket, the two most interesting picks would be Sen. Warren or Sen. Booker.

An early favorite, Julian Castro has landed in hot water when government investigators determined that Castro violated the federal Hatch Act that restricts partisan political activity by federal employees. According to The Washington Post, Castro praised Hillary Clinton during an interview conducted in his government office. While not considered a big deal by most, it would probably be an inopportune time for Hillary to pick Castro.

Politico reported that the stock of Agriculture Secretary Tom Vilsack is on the rise. What Vilsack brings to the table is that he is the popular former governor of Iowa, a key Midwest state and far away from Washington D.C.

Sen. Elisabeth Warren has continued to be effective on the campaign trail in attacking Donald Trump. Picking Warren would energize fans of Bernie Sanders and would add an element of excitement to the campaign. However, picking Warren carries some risks. Warren could end up stealing the spotlight from Clinton, and would put a progressive stamp on the campaign that would appeal to the left, but would be a hard sell for middle America.

Sen. Cory Booker would also be an appealing choice for Hillary. As just one of two African-Americans in the U.S. Senate Booker would be a powerful voice in dealing with the increasingly volatile issue of race relations. But, Booker is from New Jersey and that may be too close to New York for comfort.

In fact, geography could end up putting Tom Vilsack in the top spot. Tim Kaine, Elisabeth Warren, and Cory Booker all live within 400 miles of Hillary’s New York base which could make the rest of the country feel left out of this year’s election. Given the high level of dissatisfaction with government in the country, it might be wise for Hillary to look to middle America for her running mate.

Hillary will be in the critical battleground state of Florida later this week, and that would be a prime spot and a prime time to name her running mate.