I think a Romney nomination would be a gift to Obama's re-election bid, as Romney fits right into Obama's previously-discussed strategy of showing the Republicans will attack the things they used to support, leaving the government gridlocked and incapable of doing anything. On issue after issue, Mitt Romney has lurched significantly to the right, as has the rest of his party.
In 1994, when he ran for Senate against Ted Kennedy, Romney said he would support Sen. John Chafee's (R-RI) health care bill, which included a federal mandate to buy health insurance. He later, as Governor, put in place "RomneyCare", which includes a mandate to provide insurance.
This election, he attacks health care reform as strongly as any of his Republican colleagues. With Republican voters whipped into a frenzy over ObamaCare, to do anything else would end his chances of nomination.
In 2005, Romney was strongly involved with negotiations to set up the Regional Greenhouse Gas Initiative, a cap-and-trade system among New England states. Initially, he supported the measure, saying "I think it is good business" and "we can effectively create incentives to help stimulate a sector of the economy and at the same time not kill jobs."
This time around, he says "Cap and trade effectively constitutes an enormous, hidden tax on the American people and American businesses. It will lead to higher joblessness and make a bad economic situation even worse."
When running for the Senate in 1994, Romney stated "I believe that abortion should be safe and legal in this country." When running for Governor in 2002, he said "I will preserve and protect a woman's right to choose, and am devoted and dedicated to honoring my word in that regard."
In 2008 and 2012, he has repeatedly said he is pro-life and would support overturning Roe v Wade.
In 1994, Romney advocated strict campaign spending limits and the abolition of PACs. In 2002, he suggested public financing of campaigns through a 10% tax on private contributions to privately-funded candidates.
In 2008, he said "Do we really want government telling us when we can engage in political speech, and what form it can take". He has since been strongly opposed to McCain-Feingold and other efforts to limit campaign contributions and spending. Recently, he has received rather shady large contributions from corporations which form, give him a check for lots of money, then close.
In 1994, Romney wrote a letter (.pdf) to Log Cabin Republicans saying he supported gay and lesbian soldiers being allowed serve openly.
He recently said "Don't Ask, Don't Tell" should have been kept in place.
In the interest of brevity, I'll stop there, but he has a similar record of strong right-ward turns on issues such as gun control, immigration policy/amnesty, capital gains taxes and others.
Vast majorities of voters agree that Washington is broken. Parties that used to be able to compromise with each other are now unable to do so. A Mitt Romney nomination would be great news for Obama and Democrats because he personifies the truth that the separation between the parties is the result of the Republican Party tilting heavily to the right.
Next up, we'll get back to discussing why Obama's recent strategy of pushing for tax increases on the rich is not "playing to his base", as his critics claim.