At least two Democrats in the U.S. House will see the curtain drawn on their careers in Congress today, as four states make their choices in primaries today, kicking off primaries in 13 different states over the next four weeks.

In both Michigan and Missouri, there are member versus member matchups created by redistricting, as both of those states lost a seat in the U.S. House.

In Michigan, Rep. Hansen Clarke is facing off with Rep. Gary Peters in the Democratic Primary for the 14th District; in Missouri, Rep. Russ Carnahan and Rep. Bill Clay will battle in the Democratic Primary for Missouri's 1st District.

While two of those lawmakers will face rejection at the polls on Tuesday, there is at least one other member who is on the "red alert" list as well - veteran Rep. John Conyers.

Conyers, a Michigan Democrat who was first elected to Congress in 1964, has been worrying some supporters in recent months, but recent polls have shown him leading four challengers.

Already this year, 8 incumbents in the House have been defeated in primaries, the same number as ten years ago in 2002 when districts were redrawn after a census.

That number will go up by at least two on this Tuesday, the most since the 1992 elections, when 19 incumbents lost their primaries - that was also in the wake of redistricting after a census.

Along with primaries in Michigan and Missouri, voters will also pick congressional candidates in two other states, Kansas and Washington.

August is actually a very busy month for primary elections, as the rest of this month will see congressional choices made in Hawaii, Connecticut, Florida, Minnesota, Wisconsin, Wyoming, Alaska, Arizona and Vermont.

The last four states to hold primaries do so in September: Massachusetts, Delaware, New Hampshire and Rhode Island.

Then it is on to November.