The bad news for the few moderate Republicans still in Congress is that they face long odds in the fast-approaching 2016 elections.

The good news for Republican moderates in Congress is that a difficult 2016 cycle of Senate races now looks likely to close the book on the Tea Party era of American politics.

The hot rhetoric coming from talk radio hosts and conservative activists — whether it's trashing Planned Parenthood or praising Donald Trump’s outrageous comments about Mexican immigrants — is only making it more difficult for Republican senators trying to win centrist votes next year.

The GOP is at a disadvantage as this political game starts.

Republicans hold the Senate majority now with eight more seats than Democrats. But next year they have to defend 24 seats while Democrats are defending only 10. And they will be playing defense in a presidential election year when minorities, young people and women — major Democratic constituencies — are likely to turn out in big numbers.

The bottom line for Republicans is holding control of the Senate. The Democrats will be busy trying to win five seats to gain the majority — and only four will be required if a Democrat wins the White House, since her or his vice president would then hold the tie-breaking vote in the Senate.

The danger posed to Republicans by Tea Party politics is on display right now.

Earlier this month, the Republican majority in the Senate reacted to Tea Party passions by voting to defund Planned Parenthood, the national women’s health care service and abortion provider. The effort failed because they failed to get enough Democrats to join them to overcome a filibuster. Polls show most Americans support abortion rights.

Illinois Sen. Mark Kirk was the lone Republican senator to vote against the GOP’s defunding bill. Kirk bolted from his party’s official line because the vote would have hurt his chance of re-election. He is widely seen as the most vulnerable GOP incumbent in the country.

“In other states, tissue donation programs should be investigated, but in Illinois there is no similar program,” Kirk said in a statement to The Hill. “I do not plan to cut access to basic health care and contraception for women, the majority of whom have no other resources.”

Kirk won his seat by less than 2 percentage points in 2010, during the Republican-wave election. His likely Democratic opponent will be the popular Congresswoman Tammy Duckworth — a pro-choice, highly decorated Iraq War veteran and double amputee. The University of Virginia’s Larry Sabato now has Kirk’s race listed as a likely win for Democrats in his Crystal Ball political predictions.

Kirk is not the only vulnerable Republican moderate in the Senate. There are seven Republican-held seats up for re-election that are located in states that President Obama won in both 2008 and 2012: Illinois, Florida, Iowa, New Hampshire, Ohio, Pennsylvania and Wisconsin.

Republican senators elected as part of the Tea Party wave in 2010 are starting to draw formidable Democratic challengers.

Earlier this month, Pennsylvania’s incumbent Republican Sen. Pat Toomey drew a seasoned Democratic opponent — Katie McGinty, the chief of staff to Gov. Tom Wolf (D). Though Toomey has tried to position himself as a moderate on issues such as gun control, the former president of the right-wing Club for Growth faces an uphill climb. In 2014 — another great year for the GOP nationally — Wolf defeated the incumbent Republican Gov. Tom Corbett by nearly 10 percentage points.

Similarly, Wisconsin’s first-term GOP incumbent Ron Johnson is getting a rematch from former Sen. Russ Feingold (D). Feingold earned a reputation as a strong progressive who led the charge against the influence of money in politics. With increased attention on liberal voices such as Sen. Elizabeth Warren (D-Mass.) and increased Democratic anger over the Citizens United v. Federal Election Commission ruling, Feingold has a strong liberal base of activists and donors willing to work for him.

The difficulty facing Republican moderates in 2016 may be compounded if the party’s presidential nominee brings attention to polarizing issues such as gay marriage and abortion. And there will be another set of problems if the candidate is personally polarizing.

“The Trump phenomenon perfectly represents the culmination of populism and anti-intellectualism that became dominant in the Republican Party with the rise of the Tea Party,” veteran Republican aide Bruce Bartlett recently wrote in Politico. “I think many Republican leaders have had deep misgivings about the Tea Party since the beginning, but the short-term benefits were too great to resist. A Trump rout is Republican moderates’ best chance to take back the GOP.”

But first they would have to suffer losses for the White House and in the Senate.

The alarms for Senate Republicans are already ringing as fundraising for the cycle gets into gear.

The Democratic Senatorial Campaign Committee (DSCC) raised $1.6 million more than the National Republican Senatorial Campaign Committee (NRSC) in June.

The candidates, the parties and powerful political interests are already gearing up for a costly, negative campaign.

The Wall Street Journal’s Jerry Seib recently reported that, a year and a half ahead of the elections, the U.S. Chamber of Commerce is so concerned about holding the GOP Senate majority that they have run advertising for four Senate Republicans.

It is no secret that the right-wing base of the GOP is unhappy with Sen. Mitch McConnell (R-Ky.) as Majority Leader. But if they keep up the extreme rhetoric, they may well be longing for the days of McConnell’s leadership — that is, when Sen. Charles Schumer (D-N.Y.) becomes Majority Leader instead.