Republicans haven't always been opposed to stimulus. In 2008, under George W. Bush, congressional Republicans joined with Democrats to pass the Economic Stimulus Act, a $152 billion package which gave tax cuts to individuals and married couples, tax breaks for businesses, and $40 billion in direct spending. Going back further, again under President Bush, Republicans touted the initial round of Bush tax cuts as stimulus that would boost the economy.
Writing in response to Paul Krugman-who doesn't see political room for a hypothetical Romney administration to propose fiscal stimulus-Jonathan Chait suggests that Republicans might reevaluate their stance in the event of a GOP presidency:
[T]o whatever extent the Republicans oppose Keynesian theory right now, I don't see this as a core belief of theirs. Their true core belief is that tax rates on the rich should be low. George W. Bush and the GOP Congress were both willing to advocate stimulative Keynesian policies in 2001 and again in 2008. Romney's economic advisers share their party's obsession with cutting taxes for the rich. If the Republican Party finds itself no longer standing to benefit from economic calamity, and suddenly in a position to lose a great deal from it, I suspect they will find the advice of their Keynesian economists suddenly much more persuasive once again.
A lot of this depends on both the sincerity of congressional Republicans and the extent to which Romney try to hold to his campaign promises. I have no doubt that John Boehner, Mitch McConnell, Eric Cantor, and Paul Ryan would support a stimulus bill; their first concern is politics, and by improving the economy, Keynesian stimulus would boost President Romney and the Republican Party. But I'm not sure that the same is true of Tea Party Republicans who entered Congress in 2010; my hunch is that they're sincere about their opposition to "stimulus," and would oppose any effort to mimic the Keynesian packages of 2008 and 2009.
What's more, Romney has committed himself to a radical reduction in the size and scope of government. His campaign is based on a promise to reduce government and "unleash" the private sector, and with stimulus defined as "big government," that rules out the possibility of further spending. And while there's a chance that Romney would simply abandon his rhetoric, it would be a break from the norm; in her book Presidential Campaigns and Presidential Accountability, political scientist Michele Claibourn notes that both Bill Clinton and George W. Bush tried to address the issues they outlined in their campaigns. As she puts it, "[C]ampaigns tell us…which of the ongoing agenda items the new president is willing to expend his effort, his time, his resources."
What she means is that presidential candidates-even ones the public doesn't trust-are deliberate about the priorities they outline in a campaign, and try to pursue them once in office. When George W. Bush ran for president in 2000, more than half of the ads run by his campaign and the Republican National Committee mentioned education. "Three days after taking office in January 2001," writes Claibourn, "Bush announced No Child Left Behind…his answer to the challenge of improving education highlighted by his campaign."
Romney is running on austerity and tax cuts. Will he try to spin those policies as good for the economy? Absolutely. But I doubt he'll try to reach for another round of fiscal stimulus. Politically, in the GOP, there's just too much working against him.