"The numbers are definitely on our side, " brags Walt Witich, a Democratic Party political operative.

A GOP counterpart, Steve Letterer, responds, "There's a Republican wind blowing out there."

Both politicos are talking about the same thing-this year's bevy of congressional races, 33 in the Senate and 435 in the House of Representatives, to be exact.

The stakes are big; for the first time this century the two houses have been under split control for more than two consecutive years. Both sides think they can, at the very least, make strides towards changing that around. And this strange presidential year, both sides may be right.

Democrats like Witich, research director of the party's senatorial campaign committee, are banking on the odds. For the first time in three senate elections, Republicans up for reelection outnumber Democrats-19 to 14. With more ducks to shoot at, Democrat pols think they have a chance to win back the control of the senate they lost in 1980, although because they are down 55-45, the chances of this are slim.

Republicans, conversely, hope that they will be able to ride the coattails of Ronald Reagan and his economic recovery and bite into the Democrats 268-167 advantage in the House. Letterer has just returned from a nation-wide trip with Rep. Guy Vander Jagt (R-Mich.), chairman of the National Republican Congressional Committee, and says he found "people optimistic about the future and waiting to vote Republican. It's a complete turnaround from 1982, when everyone was depressed about the economy."

But the fanciful scenarios that dance through a politico's head, can be a far cry from what is likely. No one expects both the election of a Democratic president and, say, a turn to the right in Congress. More to the point, no one is really expecting the Republicans to make any major inroads into the Democratic majority in the House. The real action is going to be in the Senate, where a shift of six seats could return the Democrats to the top perch and return important committee chairmanships to senators like Sam Nunn (Armed Forces), Edward M. Kennedy (Labor and Human Resources), and Lloyd Bentsen (Environment and Public Works).

"The absolute best the Republicans can hope for in the House is to gain a few of the 26 seats they lost in 1982, and even that won't give them a working coalition with conservative Democrats," says Norman Ornstein, a political science professor at Catholic University in Washington, D.C. "But in the Senate they face a real challenge," Ornstein adds.

"There's a tough situation ahead of us," admits one Republican National Committee strategist, Ceci Cole. "Our incumbents are vulnerable and half of the Democratic incumbents are from bedrock Democratic states."

Democrats are especially confident because, of the 19 Republican Senate seats up for grabs, eight incumbents won their elections with 55 percent or less of the vote. The conventional wisdom held by full-time pols is that 55 is the magic number for determining whether a seat is vulnerable or not.

While Democrats have numbers on their side, however, Republican candidates in the country have a few things going for them. Not the least of which is that, for all the trends moving in their direction, the Democrats still have a lot of ground to make up.

Even in a good year, a swing of six seats is a lot-especially if they come from a party that far outdistances the other in terms of money and organization.

As a group, the Senate Republicans are now projected to outspend their Democratic opponents by an up to 10:1 margin and will reach in each state the maximum dollar figure a national party organization can legally spend. In the 1982 congressional races, the Republicans outspent the Democratic campaign committees by 4 to 1, and while the Democrats are expected to do better this time out, they won't even be able to come close to matching the GOP war chest.

What's more, even the best of Dems are envious of Republican organizational skills. Ornstein says the Republicans are better at spending their money. That is, because their funding organizations are tightly centralized, they can carefully target funds towards close races. Democratic funding organizations, by contrast, are more decentralized and those candidates who need large sums of cash are often left in the lurch while runaway winners sometimes find huge chunks of money in their treasuries when their campaigns are over.

Democrats have already unleashed a strong challenge in North Carolina and Iowa, where the most interesting races of the year have begun to shape up.