WASHINGTON • A new round of lacklustre showings by Republican candidates has reignited a debate within the GOP over whether US President Donald Trump will be a drag on the party's chances in November and should stay out of some of the country's most hotly contested races.

Inside the White House, Trump aides are mapping out plans for the mid-term elections that would offer a variety of options to Republican candidates, be it a visit from the President's daughter Ivanka Trump to a blue state or a presidential tweet for a red-state ally.

But mounting apprehension about Mr Trump's political capital lingered in Washington and on the campaign trail.

In a flurry of elections on Tuesday - from the suburbs of Columbus, Ohio, to the technology corridor in Washington state - Democrats turned out in droves and significantly over-performed expectations by posing serious challenges to Republicans in staunchly GOP districts.

Many Republican strategists viewed the results as a dark omen three months ahead of Election Day, saying they illustrate the limits of Mr Trump's ability to boost candidates, particularly in suburban areas where his popularity has suffered.

Even in Republican primaries, securing Mr Trump's endorsement was not a guarantee of electoral success.

"Nothing bodes well," said veteran Republican consultant Stuart Stevens, a frequent Trump critic. "You look at the amount of money spent on the Republican side in Ohio, the focus put on it", including a Trump rally last weekend in the district, "and you have an early warning sign. It's time for Republicans to counteract".

Mr Trump took a different lesson from the outcomes, crowing in a series of tweets that his presence on the campaign trail and his record could lift his party and prompt a "giant Red Wave". He wrote: "As long as I campaign and/or support Senate and House candidates (within reason), they will win!"

Despite Mr Trump's last-minute visit and Republicans dramatically outspending Democrats, Ohio Republican State Senator Troy Balderson was barely ahead of Democrat Danny O'Connor, an elected county recorder, in Tuesday's special congressional election in central Ohio.

The race remained too close to call on Wednesday with thousands of provisional votes still outstanding.

The razor-thin margin comes in a district that Mr Trump won by 11 points in 2016 and that Republicans have held since 1983. Mr Balderson had embraced Mr Trump in the campaign's final stretch.

Democrats need 23 additional seats to take over the House majority and two seats to take control of the Senate.

Mr Balderson was far from the only Republican who underwhelmed on Tuesday.

Representative Cathy McMorris Rodgers, a Republican from Washington state and chairman of the House Republican Conference, failed to win 50 per cent of the vote in a primary and will face Democrat Lisa Brown in November. Washington state has a nonpartisan primary process where the top two finishers move on to the general election.

Republicans working with the White House also pointed to Tuesday's elections in Kansas as the latest example of the volatility inside the West Wing. Mr Kris Kobach, the anti-immigration secretary of state who served as vice-chairman of Mr Trump's now-disbanded voting integrity commission, was endorsed by Mr Trump in the Kansas gubernatorial primary less than 24 hours before polls opened. Some aides and top Republicans had urged him to hold off on endorsing Mr Kobach, who they fear could threaten other Republicans due to his hard-line positions. The race remained too close to call on Wednesday, with Mr Kobach holding a lead of fewer than 200 votes over incumbent Governor Jeff Colyer.

Trump allies maintain that the President is the Republican Party's best asset and said his involvement will be critical to stoking the enthusiasm of base voters. "The President is a real help for the mid-terms and we should recognise that," said Representative Mark Meadows from North Carolina. "The problem is when people can't decide whether to support him or make some sort of lukewarm effort to play to the middle. You can't half-embrace the President's agenda."

The tricky balancing act facing GOP candidates is apparent on policy. On immigration, most Republicans are eager to rally Trump voters who are clamouring for a border wall to be built - and Mr Trump has been calling for a shutdown of the federal government unless Congress appropriates funds. But they also feel pressure to reassure moderates alarmed by the Trump administration's abandoned push to separate migrant children from their parents.

WASHINGTON POST