A growing chorus of Republicans has raised serious questions regarding John McCain’s electability. Should his campaign try to appeal to independents and conservative Democrats? Or should he strive to charm social conservatives, such as evangelical Christians, and fiscal conservatives?

McCain’s next big decision is choosing a running mate, which offers an excellent opportunity to turn Republican critics into supporters and to get Americans to pay attention to his campaign. What factors should influence McCain’s decision?

First, he should think of the political map. This will be a tight presidential race and McCain’s White House hopes hinge on his ability to win swing states.

Second, he needs somebody with a proven economic record. One of McCain’s biggest weaknesses is lack of experience dealing with economics. His December 2007 remark that “the issue of economics is something that I’ve really never understood as well as I should” will be a liability during the fall.

Third, McCain’s running mate should appeal to social conservatives. These individuals are willing to volunteer hundreds of hours to make sure that Republicans turn out to vote. Given that many social conservatives are not excited by McCain’s candidacy and that Sen. Barack Obama will increase voter turnout among blacks, some Southern states, such as Georgia, will be more competitive than in the past. To win the White House, McCain must energize this voting bloc.

Fourth, he should strongly consider a politician with little exposure to Washington politics. While McCain is trying to present himself as a maverick, he is still perceived by most as a Washington insider. It will be difficult to counter Obama’s campaign’s message of change if McCain chooses a running mate who is perceived as an insider.

Finally, McCain has to try to select a vice presidential candidate that will appeal to conservative Democrats and independents, especially in swing states, but without angering the Republican base.

Republican governors will be strongly considered, as they are not Washington insiders and they have executive experience. News reports suggest that the McCain team is looking at Charlie Crist of Florida and Tim Pawlenty of Minnesota. Both candidates will help McCain secure at least one of these swing states. But, selecting Crist could turn off evangelical Christians because many have questioned his pro-life bona fides. His support for stem cell research and same-sex civil unions could also be problematic.

Pawlenty has strong conservative credentials, but his recent opposition to the U.S. economic embargo on Cuba could make it difficult for McCain to win Florida.

Some reports suggest that McCain is considering Sarah Palin, Alaska’s governor. She could attract female voters, which Obama must secure to win the White House. Palin is also an expert on energy policy. Her strong social conservative views, ability to cut spending in her home state, and willingness to further develop Alaska’s energy resources make her an interesting choice.

McCain’s opponents during the primary will also be considered. Mike Huckabee, the former governor of Arkansas, is probably evangelical Christians’ first choice. He will shore up support among Republicans in the Southern states, where McCain’s campaign did not do well.

Former Massachusetts governor and entrepreneur Mitt Romney appeals to most social conservatives. Because economic issues may be voters’ main concern in November, Romney can help McCain put together a sensible economic plan, while attracting support from fiscal conservatives. Romney can also help McCain win New Hampshire, which John Kerry won by fewer than 10,000 votes, and Michigan’s 17 Electoral College votes. Romney is also very popular in the mountain states and on the West Coast. Plus he is an excellent fundraiser, an important asset in light of Obama’s formidable fundraising operations.

If his campaign wants to energize the Republican base, Romney is the strongest contender. If he wants to attract the support of conservative Democrats and independents, but without angering Republicans, Pawlenty may be the best bet. McCain’s maverick impulses may encourage him to think of individuals outside the party. While that may be too much for Republicans to stomach, he may still surprise them.

McCain’s choice will tell us a lot about the strategy the campaign will execute during the fall. More importantly, selecting a vice president will help him reassure Republicans of his conservative credentials, repackage his message and get voters excited about his campaign.

Carlos L. Yord?n is an assistant professor in the department of political science at Drew University in Madison, N.J. He has taught at Husson College and the University of Maine.