One of Ronald Reagan's favorite jokes went something like this: When outside-the-Beltway conservatives look at Washington, they see a cesspool. But once they get elected on the promise of changing Washington, they get seduced by Big Government, and suddenly, it feels more like a hot tub.

Today, Washington has become the Republicans' hot tub. So much so that many fiscal conservatives identify GOP leaders rather than Democrats in Congress as the biggest impediments to tackling Big Government.

That could have dire implications for Republicans in the 2006 elections. The latest George Washington University Battleground poll — taken six months ago, when Republicans were more popular than they are today — reveals that only 36 percent of likely voters trust Republicans in Congress to keep spending under control. This doesn't mean that the Democrats have shrugged off their reputation as big spenders, but it tells us that for many, Republican candidates are no longer a viable alternative for voters who want to restrain government.

In the last five years, congressional Republicans have become the biggest spenders on non-defense programs since Tip O'Neill's Democratic Congresses of the late 1970s. And the number of pork earmarks exploded to 15,000 in last year's budget. The last Democratic Congress in 1994 only earmarked around 1,400 projects.

Voters are now stuck with a choice between the party of Big Government (the GOP) and the party of Even Bigger Government (the Democrats). With friends like these, it's unlikely that fiscal conservatives will be eager to pull the lever for a Republican candidate in November.

A lack of enthusiasm for big-spending Republicans has hurt the GOP before, specifically in the midterm congressional elections of 1998. Then, GOP leaders had foisted upon taxpayers two budgets that abandoned the Republican Revolution's promise of smaller government and a pork-laden highway bill that dwarfed the one Reagan vetoed in 1987. Sound familiar?

Newt Gingrich predicted at the time that Republicans would gain anywhere between 10 and 40 seats. Instead, Republicans lost three seats, slicing their majority almost in half. Why? Exit polls showed that turnout for self-identified conservatives dropped 6 percent from 1994 to 1998. In a midterm election as close as 1998 — when the difference in the total number of votes received by GOP and Democratic candidates was 2 percent — Republicans needed the help of fiscal conservative voters. But those voters stayed home on Election Day.

Since history may repeat itself this November, it's worth asking whether a loss of Congress by the GOP would be a bad thing for supporters of limited government. The answer is "No." Government grows slower when at least one house of Congress is controlled by a political party different than the president's — a condition known to political scientists as "divided government."

Since 1965, government has grown slower in periods of divided government than under periods of united government. United government tends to lead to a 3.4 percent average annual increase in federal spending in real per-capita terms, more than twice the growth under divided government: 1.5 percent. When you consider how fast government grew in relation to the economy, the results still favor divided government. The average yearly increase in government above and beyond GDP growth is 25 times faster with united government than with gridlock.

Imagine how congressional Republicans would fight the sorts of big government schemes that now pepper their agenda if those proposals came instead from the mouths of Democratic majority leaders. Even President Bush might find his long-lost veto pen.

Ronald Reagan's GOP identified government spending as the problem, not the solution. Today's GOP is a party that stands beside the federal behemoth crying "Full steam ahead!" It is a party with an identity crisis.

Republicans need to clear their heads. Some time in the political wilderness — i.e., the minority — might help.

Stephen Slivinski is director of budget studies at the Cato Institute and the author of "Buck Wild: How Republicans Broke the Bank and Became the Party of Big Government."