The massive 2017 tax bill enacted before Christmas was a legislative triumph for President Donald Trump, congressional Republicans and especially House Speaker Paul Ryan, who had sought to revamp the nation’s tax system for the better part of a decade.

Whether a package of goodies that primarily helps corporations and wealthier taxpayers can become a 2018 political victory for the Republicans is another question that may prove more elusive than the GOP’s ultimately successful quest for the 50th Senate vote for its signature legislative initiatives on health and taxes.

But history — underscored by the current political climate — suggests that enactment of the tax measure will be this administration’s legislative high point, as mid-term election politics exert increasing influence and Republicans in competitive states and districts become warier of tying themselves to the unpopular President.

With the signature exception of Franklin D. Roosevelt, whose massive majorities amid the lingering Depression enabled him to maintain his influence on lawmakers well beyond his first year, presidents from Woodrow Wilson to Barack Obama have discovered their initial burst of legislative achievement was inevitably followed by either pause or resistance.

Even Lyndon Johnson, whose 1964 landslide triggered the biggest congressional majorities of any post-FDR president, began to encounter Democratic resistance in the second year of the landmark 89th Congress.

And if there was any doubt the current modest congressional Republican majorities would likely shift more from offense to defense, Senate Majority Leader Mitch McConnell, a shrewd reader of the changing political tides, signaled that at his year-end news conference.

Just days after Ryan said the House GOP would take on the always contentious subject of entitlement reform in 2018, in part to reduce a budget deficit exacerbated by the shortfall in the tax bill, McConnell shot that down.

“We’ll not be doing entitlement reform unless we have enough Democratic support to achieve it,” McConnell said in an AP interview, adding at the news conference, “There’s not much you can do on a partisan basis in the Senate.”

That’s because it takes 60 votes for the Senate to consider and pass all but the most uncontroversial legislation, unless the measure is wrapped into the budget framework as was done for both tax cuts and Obamacare repeal. With Wednesday’s seating of Alabama Democrat Doug Jones, the GOP Senate majority is down to 51-49, though Vice President Mike Pence can break a tie.

Both Trump and the Democrats have pointed to bolstering the nation’s sagging infrastructure as a top 2018 priority. But passage of any legislation is likely to be complicated by significant differences between the two parties on how to finance it and, in particular, how much federal money to provide. House Republicans are likely to be especially resistant to including any federal dollar amount close to the $1 trillion Democrats favor.

Other GOP wish list items such as revamping the nation’s welfare system, comprehensive immigration reform and yet another attempt to scrap Obamacare will have difficulty attracting much Democratic support, though some Republicans hope the minority’s quest to protect the so-called “Dreamers” from deportation may permit agreement on broader immigration curbs.

The latter issues may be the first to indicate how contentious the year will be on Capitol Hill. Lawmakers and Trump agreed to extend federal spending authority until Jan. 19 to get past the Christmas holidays without the threat of a government shutdown, creating the prospect of a major confrontation in just two weeks.

Democrats are under pressure from their Hispanic supporters to follow through on their promises to extend legal protection for the “Dreamers,” which runs out in early March, and Republicans face their own pressures to further limit immigration. Trump, meanwhile, is trying to leverage the issue to get a down payment on funds to build his cherished wall across the Southern border, though the project has minimal support from voters and Democrats and only modest backing from fellow Republicans.

The White House sought unsuccessfully to exclude immigration-related issues from Wednesday’s meeting on budget issues that included top congressional Democrats. But Trump’s taunts only intensified Democratic desire to force the matter, and how to handle that will presumably be a major topic when Trump hosts Ryan, McConnell and other GOP congressional leaders this weekend at Camp David.

Some Republicans may believe bipartisanship is unnecessary after passing the tax bill without Democratic support. But the patterns of history — plus Trump’s continuing low job approval — suggest that is a prescription for failure in a Congress likely to achieve little this year at best.

Carl P. Leubsdorf is the former Washington bureau chief of the Dallas Morning News. Readers may write to him via email at: