For the last 18 months, politicians and congressional campaign committees have been raising money for what could be a historic 2008 election. Fundraising never stops, but it’s now time to spend the money.

Enjoying huge fundraising advantages, Democrats will be spending more than Republicans. Recently, the Democratic Congressional Campaign Committee (DCCC) reserved almost $35 million in television ad buys in 31 districts. Most of the buys, which would run this fall, target GOP-held seats.

Simply put, it is a good cycle to be a Democratic fundraiser. The DCCC has nearly a 6-to-1 cash-on-hand advantage over the National Republican Congressional Committee (NRCC), while the Democratic Senatorial Campaign Committee (DSCC) holds an edge of nearly 2 to 1 over the National Republican Senatorial Committee (NRSC).

The DSCC has given $5 million to state parties to bolster ground operations, according to The Washington Post.

Republicans can’t be as bold with their money, knowing they will need to save a lot of it for the fall.

GOP campaign chiefs say they will have enough to compete, but acknowledge that the Democrats’ advantage is significant.

Because of their limited resources, Republican operatives will have to make some difficult decisions. Will they mostly protect targeted GOP incumbents? How many resources will they put into open seats? Will they spend a lot of cash going after many of the Democrats who were swept into office in the blue wave of 2006?

In the past, a few House Republicans like ex-Rep. John Hostettler (Ind.) would count on the NRCC coming to their rescue. That is no longer the case.

Unless a race is tight, GOP campaign committees are unlikely to get involved. It is hard to imagine, for example, the NRSC using its resources to help Jim Gilmore (R) in his uphill battle against Mark Warner (D) to replace retiring Sen. John Warner (R-Va.).

Senate Republicans had high hopes of taking out several incumbents this cycle, including Sens. Tim Johnson (D-S.D.) and Mark Pryor (D-Ark.). But the only Democratic incumbent considered vulnerable is Sen. Mary Landrieu (La.).

Meanwhile, more than a handful of Republican incumbents are sweating out their reelection races, including Sens. Norm Coleman (Minn.), Elizabeth Dole (N.C.), Mitch McConnell (Ky.), Gordon Smith (Ore.), Ted Stevens (Alaska) and John Sununu (N.H.).

DCCC Chairman Chris Van Hollen (Md.) has noted that following a wave election like 2006, the majority party usually loses seats.

But he predicts that Democrats will make history by growing their majority in the lower chamber, though he has stopped short of predicting how many seats they will gain.

Anything can happen over the next few months, but at this point, Democrats look like they will win 10 to 20 seats in the House and a handful in the Senate.