Survival of the fittest. Extinction of the weakest. That's Darwin's theory of evolution.

In Chicago politics, the Republicans are the contemporary equivalent of the brontosaurus. In a city with a population of 2,695,598, Republican Mitt Romney got 148,181 votes on Nov. 6, or 14.4 percent of the 1,028,870 turnout. That's 1,074 fewer than John McCain's total of 149,255 votes (13.6 percent) in 2008 and 39,876 fewer than George Bush's total of 188,057 votes (18.2 percent) in 2004.

Romney got 14.4 percent of the actual vote and 10.8 percent of the registered vote. Based on that trajectory, the Republicans will soon be garnering fewer votes than the Green Party.

However, the Democrats should not be too sanguine. Barack Obama got 930,666 votes in Chicago in 2008, and his vote dwindled to 853,102 in 2012, a drop-off of 77,564 votes. That means that Obama got 82.9 percent of the actual vote and 62.5 percent of the registered vote.

Consider this: A total of 335,501 registered voters (24.5 percent) didn't cast a ballot in November, and in 2008 the number was about 290,000. In the 2011 mayoral election, only 590,357 voters cast a ballot, so almost 57 percent stayed home. The Republicans can take some solace and boast that 37.5 percent of Chicago's registered voters did not vote for Obama and that 76 percent didn't vote for Rahm Emanuel in 2011.

But the Republicans have no beachhead in Chicago - with only a single ward where they can garner more than 40 percent of the vote and three where they can get more than 30 percent. There are no Republican aldermen and only one Chicago Republican state representative, Mike McAuliffe. Emanuel won 40 of 50 wards in 2011, while the South Side pro-Daley strongholds -- the 10th, 11th, 12th, 13th, 14th, 19th and 23rd -- produced majorities for Gery Chico.

The top Romney ward in November was the Northwest Side 41st Ward, which gave the Republican 44.8 percent of the vote, up from McCain's 43.4 percent in 2008. In the nearby 45th Ward, a working-class, overwhelmingly white bastion, with pockets of liberals in Portage Park, Romney's 29.9 percent of the vote was less than McCain's 31.4 percent. Three of Romney's "best" wards were the Rogers Park 50th Ward, with a large Orthodox Jewish population, which gave Romney 30.8 percent, up from 29.7 percent in 2008, the upscale Gold Coast 42nd Ward, filled with rich white people, which gave him 35.4 percent, up from 27.6 percent in 2008, and the Far Southwest Side 19th Ward, which runneth over with Irish city workers and which gave him 34.8 percent, up from 33.3 percent in 2008.

Romney got fewer votes than McCain in every other ward, but in almost every ward, Obama, too, got fewer votes than he received in 2008. So it can be concluded that Chicago has both a one-party and a no-party system.

In the past two presidential elections, the Democratic candidate averaged 891,000 votes and the Republican candidate averaged 148,500 votes. Any Democrat, dead or alive, indicted or convicted, will beat any Republican. Anti-Republican antipathy is pervasive, if not universal.

However, in nonpartisan municipal elections, Chicago has a no-party system. Chico got 141,228 votes in the 2011 mayoral election, almost the same number as the Romney-McCain base. Emanuel got 328,331 votes (55.3 percent of the total cast), more than 550,000 fewer votes than the Obama base. "He's been dictatorial," Alderman Nick Sposato (36th) said of Emanuel, adding that the mayor has made other aldermen "afraid to stand up." Sposato, whose ward was cannibalized and obliterated in the City Council's 2011 remap, is part of the so-called "Progressive Caucus," composed of 10 aldermen who he said are "not under the thumb" of Emanuel.

Note this: Emanuel is not unbeatable in 2015. He has alienated the Chicago Teachers Union and the Service Employees International Union, which have money and manpower, and the Southwest Siders are still unhappy. He could be beat.

Fifty-two years ago, in the 1960 Kennedy-Nixon presidential election, the storied political machine of Mayor Richard J. Daley struggled mightily to corral Democratic votes. Kennedy won Illinois by 8,858 votes, in part because Chicago machine precinct captains, especially on the West Side, cast the votes of dead people. Kennedy carried Chicago by more than 500,000 votes and Cook County by 318,736 votes.

Obama didn't need precinct captains or voter fraud to win Chicago. All he needed was the opening of the polls. Like lemmings trudging over the cliff, the vast bulk of Chicagoans vote Democratic religiously and habitually. The Republican brand name is as toxic as anthrax, and as has been the case since the 1930s, as Chicago goes, so goes Illinois.

Illinois' population under the 2010 census is 12,830,630, Chicago's is 2,695,598, and Cook County's is 5,194,675. There are 7,506,073 registered voters statewide and 2,704,993 (36 percent) in Cook County. The arithmetic is simple: If a Democrat gets 80 percent of the Chicago vote, he or she wins Cook County by 600,000-plus votes, which is more than enough to overcome the dwindling Republican margins in the Collar Counties and Downstate and to win statewide. A victory in Cook County by any Republican is now a fantasy.

In the 2012 countywide election, Republican candidates performed dismally. In the race for state's attorney, incumbent Democrat Anita Alvarez, despite the negative fallout from her bungling of the Koschman case prosecution and the embarrassment of having a special prosecutor appointed to investigate whether her office and the Chicago police exhibited favoritism toward the Daley family, won by 1,235,493-408,561 over Lori Yokoyama, who got 24.9 percent of the vote. In the race for clerk of the Circuit Court, embattled incumbent Democrat Dorothy Brown, despite a nasty primary, won by 1,114,808-475,853 over Diane Shapiro, who got 29.8 percent of the vote. In the race for record of deeds, Maywood state Representative Karen Yarbrough won by 1,135,379-369,155 over Sherri Griffin, who got 24.6 percent of the vote. Amazingly, the obscure Shapiro, the 46th Ward Republican committeeman, got 10,000 more votes than Romney. All of the Democrats ran 175,000 to 300,000 votes behind Obama.

In what may be a harbinger of the future, the Green Party candidates for Metropolitan Water Reclamation District commissioner, arrayed against Democrats Debra Shore (711,095 votes), Kari Steele (614,911 votes) and Patrick Daley Thompson, the grandson and nephew of the former mayors (622,191 votes), got an average of 140,000 votes while the Republicans averaged 358,000 votes. There was a time, as recently as 2006, when a white Republican (Tony Peraica) could get nearly 45 percent of the vote against a flawed black Democrat (Todd Stroger), but those days are over.

Clearly, for dissidents, voting "green" appears to be more palatable than voting Republican.

As recently as 1998, the tried-and-true electoral mathematics were this: A Republican wins statewide by losing Chicago by fewer than 500,000 votes, breaking even in the Cook County suburbs, winning the Collar Counties by 350,000 to 400,000 votes and carrying Downstate by 100,000 to 150,000 votes. In 1998 Republican gubernatorial candidate George Ryan won statewide by 119,903 votes because he slashed socially conservative Glenn Poshard's Chicago plurality to 238,237 votes and lost Cook County by 128,254 votes. Ryan won the Collar Counties by 248,167 votes and lost Downstate by 3,589 votes. Republican Peter Fitzgerald, challenging controversial U.S. Senator Carol Moseley Braun, a Chicago Democrat, won by 98,545 votes, with a different calculus: He lost Chicago by 407,189 votes and Cook County by 394,161 votes (265,907 more than Ryan) and he won the Collar Counties by 164,442 votes (83,725 fewer than Ryan), but he ran gangbusters Downstate, winning by 328,264 votes (324,675 better than Ryan).

There are some Republican exceptions. In 2010, when the statewide turnout was 3,792,770 (50.5 percent of registered voters), Republicans Dan Rutherford and Judy Baar Topinka won for treasurer and comptroller, respectively, but in 2012, as in 2008, turnout exploded to about 5.5 million (70 percent of registered voters), and the Democrats swept.

In 2010, 1.8 million fewer people voted, and Rutherford and Topinka faced obscure black opponents. Rutherford held Democrat Robin Kelly's Cook County margin to 387,353 votes and won statewide by 161,049 votes. Topinka, who lost Cook County to Rod Blagojevich in the 2006 governor's race by 508,605 votes, held David Miller's Cook County margin to a mere 209,549 votes and won statewide by 429,876 votes.

Overall, Rutherford got 1,811,293 votes and Topinka got 1,927,139 votes, which was in the realm of Romney's 2,090,116 votes. In other words, when 1.6 million pro-Obama, pro-Democratic voters don't vote, and when the Democrats run marginally electable candidates, the Republicans can win statewide.

In the 2010 U.S. Senate race, Republican Mark Kirk got 1,778,698 votes, lost Cook County by 456,722 votes, but won statewide by 59,220 votes. In the 2010 governor's race, Bill Brady got 1,713,385 votes, lost Cook County by 500,533 votes, and lost to Pat Quinn statewide by 31,834 votes.

The bottom line: Republicans can win if (1) statewide turnout is under 3.8 million, (2) they lose Cook County by 450,000 or fewer votes, (3) they run against unknown and underfunded Democrats, and (4) they run an unflawed, minimally acceptable candidate. Despite their Chicago collapse, the Republicans still have a statewide window of opportunity. In Cook County, however, that window is nailed shut; in Chicago, it doesn't exist.