Donald Trump wants to build a giant wall, and so do many Republicans, but not the one he has in mind. Their wall is to protect them from what they increasingly believe will be a humiliating defeat for their presidential nominee and – possibly – catastrophic losses for congressional Republicans.Speaker of the House Paul Ryan (R-Wisconsin) has sent out a frantic call for deep-pocket Republican donors to dig deeper because Trump is putting the House GOP majority in danger.Over in the Senate the chances are better for a Democratic takeover.They live in justifiable fear – which the Democrats call hope – that Trump is an albatross around GOP necks and may cost them their control of Congress.Republicans won those majorities as a result of close attention to the grass roots, focusing on elections of governors and state legislators, the folks who draw up congressional districts in most states.For all of Hillary Clinton’s talk about working with Congress, there’s little she can achieve if the Senate is still controlled by Republicans. Unless she brings in a Democratic majority, Sen. Mitch McConnell (R-Kentucky) will be running the show, and there is no reason to think he’s about to change his practice of the past eight years – block anything and everything the Democratic president wants and then blame the White House for the gridlock in Washington.One longtime Democrat put it best: “The R’s invented congressional constipation and then blamed it on the Dems and got away with it.” Someone finally explained to Trump last week that his attacks on fellow Republicans are only helping the Democrats, so he did a 180 and reluctantly read a perfunctory statement endorsing Ryan and Senators Kelly Ayotte (New Hampshire) and John McCain (Arizona). Someone must have told old know-it-all that he needs those senators more than they need him. (Susan Collins of Maine is the latest Republican senator to announce she won’t vote for Trump.) Bret Stephens, a Wall Street Journal editor (and former Jerusalem Post editor), called Trump “a millstone” around Republican necks. “Republicans in most Senate battlegrounds are running ahead of Trump in their states,” and they’re scared he’s going to drag them down to defeat, according to 538.com.The fervent prayer of many Republican candidates is that the public will not blame them for Trump when they go into the voting booth.Republicans have a 54-46 majority in the Senate, so a switch of five seats would make Sen. Chuck Schumer (D-New York) the first Jewish majority leader of the Senate. (Only four would be needed if there’s a Democratic vice president to break tie votes.) The latest NBC/WSJ poll shows voters nationally want to see Democrats control the 115th Congress next year by a four percent margin.The Senate is very much in play, less so the House.Democrats need a turnover of 30 seats for a simple majority of 218. That’s no easy task since many more Republicans than Democrats are solidly gerrymandered into safe seats. That’s because the GOP has done much better job of focusing on statehouse elections, and it is the governors and legislatures that draw up most of the congressional district lines.Democrats say they’re waking up to the gerrymandering issues and launching a major coordinated campaign effort with the state parties and the congressional campaign committees to focus on down ticket races this year and preparing for redistricting following the 2020 census.They have a lot of catching up to do. So far they lack an effective 2020 ground game in place. Democrats suffered massive losses in state legislatures, governors’ offices and the Congress during the Obama years. The president has said reversing that trend will be a top post-presidency priority. One veteran Democratic operative told me that Clinton does not yet seem to have a Senate strategy, but that may change as new leadership takes over at the DNC.Republicans, however, already have a large, well-funded and effective conservative support network in the media, business groups and think tanks focusing on “the shifting US political terrain,” VOX reports.In today’s super-polarized climate, there is less ticket splitting than in previous years, something that should help Democrats. But it’s not enough for Democrats to sit around wishing and praying for Trump to self-destruct and take down his party’s congressional majorities with him.After Mitt Romney’s devastating defeat in 2012, the GOP did an “autopsy” of the election and a major finding was the need to reach out to minorities, particularly Hispanics. Their new standard bearer’s racist rants against Mexicans and other Latinos and the way his campaign has energized the white supremacist underground has blasted that strategy to smithereens, and the consequences could well be felt in the crucial race for control of Congress.The Democrats, suffering a string of losses at the congressional level during the Obama years, are a minority in the Congress and a majority in the country. If they want to be more than the party that wins the White House every eight years or so, they need to do their own autopsy and implement the results by putting their full focus on rebuilding their grass roots.