That our troop strength is maintained regardless of our casualties is never portrayed as proof the enemy is losing or lying about our losses.
But I digress. Since few wars are won by physically annihilating an enemy, troops strength is not a measure of winning. It is not a bad sign that the enemy maintains its strength. When we start to finally near victory, then enemy strength will dwindle. I dare say Nazi Germany probably had more men under arms in January 1945 than September 1939. In any case, Strategypage notes:
While many Sunni Arabs are willing to go along with this democracy thing, a well armed and ruthless minority is not. There aren't many of them. Using data from interrogations, electronic eavesdropping, and statistical modeling, there are perhaps 20,000 Iraqis willing to use, or actively support, violence against the government. Offer some cash, which the ringleaders of the violence do, and you can generate several dozen incidents a day. That includes bombings, political kidnappings (as opposed to the more numerous criminal ones), threats (trying, with not much success, to discourage other Sunni Arabs from working for the government) and beatings and murders of those who will not cooperate.
There is that 20,000 number that I've heard before. Is this drawn from the same sources that call our enemy at 20,000 strong? But it is not actually the same as 20,000 combatants occasionally cited. Lumping active supporters, the logistics tail of the insurgents, in with the trigger pullers and bombers, misleads, I think.
But these thugs and their supporters are running out of room to hide. They will at some point break, and the willing and active supporters will drift away leaving only those who will never qualify for an amnesty to flee Iraq or die in place. And with the success we've had in building the Iraqi army (but with challenges remaining with much of the police force, admittedly), those last ones will be hunted down by Iraqi soldiers.