AP PHOTO Former Pennsylvania Sen. Rick Santorum speaks to a group of pro-life citizens Thursday in Windsor Heights.

WINDSOR HEIGHTS — Former Pennsylvania Sen. Rick Santorum argued Thursday that only a sharply conservative Republican message can ‘‘stem the tide’’ of change President Barack Obama is seeking in Washington, and he wants to play a role in that debate. During a visit to Iowa, where precinct caucuses start the presidential nominating process, Santorum said he hasn’t decided whether he will seek the Republican nomination for president in 2012, but he’s considering a return to politics. Santorum lost his Senate re-election bid by a large margin in 2006. He was in Iowa at the invitation of the American Future Fund for a speech Thursday night in Dubuque. ‘‘One of the reasons I accepted the invitation is I want a role in where this party is going, where this country is going,’’ Santorum said in an interview with The Associated Press. ‘‘Whether it’s a role in a political fashion, whether it’s a role as a commentator or a role as a party leader, I don’t know and it’s not important to m.