Hillary Clinton is expected to name her running mate Friday in advance of the Democratic National Convention in Philadelphia which starts Monday.  

While there are many names being floated around from cabinet secretaries to former governors, here is a comprehensive countdown of who is the most likely vice presidential selection and why.  

1. Virginia Sen. Tim Kaine By many  accounts, Kaine is the front-runner in the veepstakes, and has received the backing  of former President Bill Clinton — and there are valid reasons why. As a former governor of a state that has become increasingly purple, he can certainly help deliver Virginia. He also speaks fluent Spanish and delivered the first Senate floor speech in the language when debating immigration.  

But selecting Kaine also has significant downsides for liberals. For one, he voted for Trade Promotion Authority, also known as “fast-track authority,” which would make trade deals like the Trans-Pacific Partnership subject to an up-or-down vote without the ability to amend. While Clinton came out against the TPP last year, this would raise questions about her commitment to opposing the deal.  

2. Agriculture Secretary Tom Vilsack Vilsack’s name has been a latecomer to the veepstakes. However, he has a long political history. He is the former governor of Iowa, a swing state, who ran an aborted presidential campaign for the 2008 cycle and ultimately endorsed Clinton.  

However, Vilsack is largely unknown, and he has earned the scorn of a few environmentalists. As soon as his name was floated, the environmental group Friends of the Earth Action criticized him for his support of some GMOs. He has also supported the Trans-Pacific Partnership, which won’t earn him any fans on the left.  

3. New Jersey Sen. Cory Booker Booker has many positive traits that could appeal to the new generation of Democrats. The former mayor of Newark has earned a massive social media following and much media attention after feats like rescuing a freezing dog, and a neighbor in a burning home. He has also been one of Clinton’s most passionate surrogates on the campaign trail both in and out of New Jersey.  

But Booker lacks the depth of experience that many of the other potential running mates have. Also, despite his tenure as mayor of Newark earning him much media attention, his record was mixed. Booker has also been accused of being too close to the financial industry, having been one of the top recipients of Wall Street cash in 2014.  

4. Labor Secretary Thomas E. Perez The son of Dominican immigrants, Perez is a favorite among progressives. Under his time as secretary, the Department of Labor doubled the salary threshold for overtime pay. He is also a champion of raising the minimum wage and paid family leave.  

But Perez may be seen as too far left by some. His confirmation as Labor secretary was met with vehement opposition from Republicans and he was only confirmed after a deal was reached to confirm seven Obama nominees.  

5. Housing and Urban Development Secretary Julián Castro Like Booker, Castro is a young, charismatic former mayor — in his case of San Antonio. His twin brother Joaquin is a congressman from Texas and both are graduates of Stanford and Harvard Law School. Castro delivered the keynote address at the Democratic National Convention in 2012 and would be the first Latino vice president.  

But Castro was recently found to have violated  a campaign ethics law known as the Hatch Act by touting Clinton’s candidacy while a federal employee. Also, outside of his time at the department, he has very little experience on the national stage. He also doesn’t have any statewide experience as a Democrat in deep-red Texas.  

6. Massachusetts Sen Elizabeth Warren Nobody excites the progressive base more than Warren. For months, progressive groups like MoveOn.org and Democracy for America tried to encourage her to run for president. But Warren soon faded from speculation and as of Thursday night, she told TV host Stephen Colbert “I think if it were me, I would know it by now, so probably not.”  

A former Harvard Law professor, the Consumer Financial Protection Bureau created under the 2010 Dodd-Frank financial reform law was her idea. She is also one of the most vicious attack dogs against  Donald Trump, calling him a “small, insecure money-grubber.” But Warren may be too critical of Wall Street for Clinton, who has longstanding ties to the industry. She was also not afraid to criticize President Obama when he nominated Wall Street banker Antonio Weiss to the Treasury department and succeeded when Weiss ultimately withdrew his nomination.  

Lindsey McPherson contributed.