If you’ve been reading the latest New York Times/CBS poll numbers – Only 25% in Poll Approve of Congress – you might well wonder why despite all this, political insiders remain so confident that only a tiny percentage of members will be defeated at the polls in November.

The answer lies in the two big assets incumbents have going for them this election year: safely drawn congressional districts and cold, hard cash. In fact, if 2006 is supposed to be a tougher-than-normal year for incumbents, somebody forgot to tell the interest groups that fund congressional campaigns.

According to the latest contribution totals at Open Secrets, the 20 biggest industries giving money to congressional candidates have an overwhelming preference for incumbent office-holders. Some 77% of their combined contributions so far this election cycle have gone to candidates already in office. (You can find the exact totals for each industry by selecting an industry and clicking the link for “Money to Congress.”)

Three industries – electric utilities, pharmaceuticals, and lobbyists – have given more than 90% of their money to incumbents. Only four gave less than 70% to incumbents: leadership PACs, candidate committees, education and retirees.

Here’s the breakdown of the 20 most generous industries and interest groups this election year, sorted by their preference for incumbents. (The figures are derived from the numbers on Open Secrets.)

Of course, one reason so many industries give money to incumbents is that they’ve made substantial investments in their careers. Contrary to what some voters may think, gangs of lobbyists do not prowl the halls of the Capitol with bags of cash the night before a big vote. Cultivating Congress is a painstaking process that takes a lot of money and a lot of time. Don’t think one-night stand; think long-term relationship.

With House campaigns averaging a million dollars apiece, and Senate races costing many times that amount, members of Congress never really stop raising campaign cash.

One of the most reliable ways they do that is through fundraising events in Washington, DC. Such events are going on practically every day Congress is in session, especially as the calendar creeps closer to Election Day. You can get a taste of the fundraising frenzy by checking the list of upcoming events at the website of the National Republican Congressional Committee, the GOP’s fundraising arm for House members.

Since Congress tends to schedule votes only between Tuesday and Thursday, the biggest action is in the middle of the week. Earlier this week, for instance, the NRCC listed only one fundraiser on Monday and one on Friday, but 14 on Tuesday, 22 on Wednesday and 16 on Thursday.

That’s a total of 54 fundraisers in one week – and that’s just for House Republicans! The Democrats are more circumspect about listing their members’ fundraising events online, as are Senate Republicans.

Most of the news of those events travels discretely through emails and faxes to a closed audience of lobbyists and PAC directors – the ones most likely to show up, check in hand. My colleague Bill Allison has been collecting some of those faxed invitations and it’s easy to see why these things don’t circulate to the public at large. The invitations typically list the member’s name – with their committee assignments prominently featured. The mailing list then targets the very industries those committees regulate.

It’s a closed system, quite efficient in its own way, and with the ever-rising cost of campaigns, both sides – members and contributors – are mutually dependent on each other.

What it all boils down to is this: if there’s anyone who feels the pain of incumbents in this difficult year, it’s the industries and interest groups who’ve invested so heavily in their careers.