Like Obama? Vote for Gingrich.

Registered Democrats and independent voters in 16 states can take it easy during the primary season. Democrats already know President Obama will be their nominee in 2012, and independents can’t vote in states with closed primaries or caucuses that only permit those enrolled in a party to vote. 

In most states, however, unaffiliated voters can vote in either party’s primary, and partisans, in some cases, can cross party lines to vote in the other party’s primary. In these states, which include Texas, Ohio, and Illinois, Obama supporters should show up and vote in the Republican primary – and, for strategic reasons – they should vote for Newt Gingrich.

Many people are unaware that there is considerable variation in primary election systems – across both states and parties. The Supreme Court has ruled that states cannot dictate primary election participation rules to parties, and parties in many states do not restrict participation to partisans. So Democrats in these non-closed primary states can show up and vote in the Republican contests. Given the shear number of Democrats in these states, their influence in Republican contests can be considerable.

Once voters get to the polls to vote in primary elections, they generally have two voting options: They may vote sincerely – that is, for their top choice – or strategically. For Obama supporters, a sincere vote for the president in the Democratic primary would essentially be wasted.

That leaves Obama supporters with a strategic vote. Strategic voters cast votes that help their first choice indirectly. This happens by influencing, for example, who their preferred candidate’s opponent will be in the general election.

This practice was so common in the past that many New Jersey Democrats in the 1930s, for example, became known as “one-day Republicans” and were openly wooed by Republican candidates during the primaries.

Mr. Gingrich is the best choice for Obama supporters voting strategically in primaries. The former US House Speaker generally fares worse than his Republican contenders against Obama in head-to-head poll match-ups looking ahead to the general election.

Maybe it’s the baggage – his track record of volatility, concerns about his character or his personal life, or perceptions that he is too extreme in his ideological views for many Americans. Whatever the reasons, such a weak Republican nominee (even with a Rick Perry endorsement) would be the ideal opponent for Obama – in the eyes of those who would like to see the president re-elected.

There is surely no love lost between Newt Gingrich and Obama supporters. But the latter have every incentive to do their part to assure Gingrich will eventually emerge as the nominee, and, for his part, the speaker may wish to woo them.

Costas Panagopoulos is associate professor of political science and director of the Center for Electoral Politics and Democracy at Fordham University.