THE PROBABLES:

Sen. Rob Portman of Ohio, 56

PRO: Former legislative affairs director for President George H.W. Bush, U.S. trade representative and budget director for President George W. Bush, congressman, senator. Rarely invites controversy, soft-spoken, won big in his 2010 Senate bid in a state crucial to the election.

CON: Too closely aligned to Bush and the struggling economy. Portman presided over the fiscal 2008 federal budget, which more than doubled the deficit. Style may be too bland.

Tim Pawlenty, former Minnesota governor, 51

PRO: Compelling bio: His mother died when he was a teenager and his father was laid off from his trucking company job. He’s the first in his family to graduate from college. An evangelical, he was seriously considered for the 2008 VP slot. Strong conservative Republican credentials in a Democratic-dominated state.

CON: Unexciting. The state probably isn’t in play. His presidential campaign fizzled in 2011, and he was a sharp critic of Romney’s Massachusetts health care plan – which would be duly noted by the Obama campaign.

Rep. Paul Ryan of Wisconsin, 42.

PRO: A star among conservative Republicans for the budget plan he authored in the House of Representatives and his willingness to take on entitlement spending while advocating tax cuts.

CON: Romney could be open to attacks by the Obama campaign that he doesn’t care about the poor and wants to dismantle popular safety net programs.

Gov. Bobby Jindal of Louisiana, 41

PRO: An Indian-American two-term governor and Rhodes Scholar who could add ethnic and regional diversity. A rising star regarded as a problem solver in the aftermath of Hurricane Gustav in 2008 and the Gulf oil spill in 2010.

CON: Bombed on the national stage when he delivered the Republican response to Obama’s 2009 State of the Union speech. Initially supported Texas Gov. Rick Perry’s presidential run. Wrote in 1994 about attending the dorm-room exorcism of a friend.

THE MAYBES:

Sen. Kelly Ayotte of New Hampshire, 44

PRO: A down-to-earth first-term senator liked by conservatives. A former state attorney general who developed a reputation as a crime fighter. Could help Romney close a gender gap with Obama.

CON: No experience on a national stage and could have a hard time convincing voters she’s ready to be president. Not a compelling speaker. Her state, while considered a tossup, only carries four electoral votes.

Sen. Marco Rubio of Florida, 41

PRO: A conservative favorite who could provide a jolt of youthful enthusiasm and improve Romney’s standing with Hispanics.

CON: A freshman senator with less experience than the other contenders. Appeal outside Cuban-American voters is questionable. He has an uncertain rapport with Romney – Rubio only endorsed him as the Republican primaries began to wind down. News reports that as a former Florida house speaker Rubio charged personal items to a state party credit card could provide a distraction.

LONGSHOTS:

Gov. Chris Christie of New Jersey, 49,

PRO: Has an everyman persona. An eager combatant who’s taken on teachers unions.

CON: The potential to outshine Romney. His bombastic style could wear thin with voters and cause problems for the campaign.

Former Secretary of State Condoleezza Rice, 57

PRO: George W. Bush’s national security adviser and secretary of state has foreign policy credentials Romney lacks. An African-American woman who could attract white moderate and independent voters.

CON: Closely tied to Bush and the wars in Iraq and Afghanistan; a moderate on abortion and affirmative action. She’s never engaged in partisan politics.

NO WAY NO HOW:

Former Sen. Rick Santorum of Pennsylvania, 54

PRO: Loved by evangelicals and social conservatives for his fierce stance against abortion and for traditional marriage.

CON: Aggressively campaigned against Romney before bowing out and giving Romney a half-hearted endorsement.

Former House Speaker Newt Gingrich, 69

PRO: Considered a big thinker by supporters; a fiery orator who’d deliver plenty of anti-Obama red political meat.

CON: A Gingrich-related “super PAC” attacked Romney during primaries, which provided fodder for Obama’s campaign. Considered too impulsive and unpredictable.

Gov. Nikki Haley of South Carolina, 40

PRO: Indian-American conservative who could help Romney woo women and add ethnic and geographic diversity to the ticket.

CON: Endorsed Romney and watched him lose South Carolina by double digits to Gingrich. Has a combative relationship with the state’s Republican-controlled legislature. She was recently cleared of allegations that she used her office for personal gain and lobbied for employers.