"As Democrats launched on Thursday a fierce attack against John McCain over his wealthy lifestyle, Mitt Romney must have looked on with alarm.

The former governor of Massachusetts is among the frontrunners for the Republican vice-presidential nomination, which Mr McCain is likely to announce next week.

But the choice of Mr Romney may suddenly have become more risky if the Democrats plan to make wealth a campaign issue.

As co-founder of Bain Capital, one of the biggest US private equity companies, Mr Romney is worth up to $250m (€170m, £130m).

His presence on the Republican ticket would make it easier for Democrats to portray the McCain campaign as out of touch with ordinary Americans.

Mr McCain's wealth - which stems from his marriage to the heiress of a large Arizona beer company - came under scrutiny this week after he appeared to forget during a press interview how many homes he and his wife, Cindy, owned.

The McCain campaign later said he owned at least four but media reports suggest the true number could be as high as eight.

Seizing on the gaffe, Barack Obama, the Democratic presidential candidate, contrasted Mr McCain's property portfolio with the pressure facing ordinary homeowners amid turmoil in the housing market.

Similar taunts could be levelled against Mr Romney, who owns a mansion with tennis courts in Massachusetts, a lakeside house in New Hampshire and a cabin in Deer Valley, a posh Utah ski resort.

Mr Romney is generally viewed as joint favourite to become Mr McCain's running mate, together with Tim Pawlenty, the conservative governor of Minnesota.

Mr McCain is likely to announce his choice soon after the end of the Democratic convention on Thursday in an attempt to seize attention from Mr Obama ahead of the Republican convention the following week.

Other contenders include Rob Portman, a former Ohio congressman whose potential to help carry his crucial home state must be weighed against his ties to the unpopular Bush administration as a former White House economic adviser.

Mr McCain could try to undercut Mr Obama's promise of change by picking a young and reform-minded Republican such as Bobby Jindal, the 37-year-old Indian-American governor of Louisiana. He could appeal to women by choosing Sarah Palin, the young governor of Alaska, or Meg Whitman, former CEO of Ebay.

Mr McCain recently floated the possibility of reaching out to moderates with a pro-abortion pick such as Tom Ridge, the former Pennsylvania governor, or Joe Lieberman, the Democrat-turned-independent who was Al Gore's running mate in 2000.

But that prospect appears to have waned after protest from activists, who warned that Mr McCain must pick a firmly anti-abortion candidate or risk alienating evangelical voters.

Some analysts believe the threat of a pro-abortion running mate was calculated to make the religious right more amenable to Mr Romney as a compromise.

Mr Romney promoted himself as an anti-abortion social conservative during the Republican primaries but some evangelical voters remain suspicious of his inconsistent record on abortion and his Mormon faith.

He was the strongest challenger to Mr McCain for the Republican nomination and the hostility between them became one of the main storylines of the primary campaign.

The men have since buried their differences and Mr Romney has emerged as one of Mr McCain's most forceful and effective advocates.

"I'm appreciative every time I see Mitt on television on my behalf," Mr McCain said at a fundraiser. "He does a better job for me than he did for himself, as a matter of fact."

As running mate, Mr Romney's business background could help compensate for Mr McCain's self-acknowledged weakness on economic issues at a time when the slowing economy is topping the list of voter concerns." (Andrew Ward, The Financial Times, August 23, 2008)