Donald Trump unveiled the delayed results of his $14m renovation of Washington DC’s Lincoln Memorial reflecting pool in what is expected to be his final press conference before voters head to the polls for the midterm elections.

On the eve of a consequential election day, with polls indicating that most voters feel the US president has grown too focused on building projects in the nation’s capital, he stood in front of the newly opened reflecting pool to discuss – in detail – changes to the pool’s pipe, the grass surrounding the area and granite.

“This project should be a project that unites all Americans,” Trump told reporters on Monday afternoon.

It has proven anything but. After Trump’s first revealed his “beautiful” makeover of the reflecting pool in June, a massive algae bloom turned it green (instead of the promised “American flag blue”) and the coating started to peel away.

Trump alleged that vandals were to blame, although his administration failed to produce evidence to substantiate such claims. While former Olympic canoeist David Hearn was initially charged over alleged damage, the office of the US attorney Jeanine Pirro later dropped the case, infuriating the president.

Hearn’s attorneys said the case’s dismissal “does not erase the abuse of government power in arresting and charging a patriotic American who did nothing wrong”.

On Monday, Trump accused his Democratic predecessors, Joe Biden and Barack Obama, of overspending on previous renovations to the reflecting pool and once again, without evidence, accused vandals of purposefully damaging the Trump administration’s renovations.

Roughly 20 minutes into his remarks on the reflecting pool, less than 24 hours before Americans head to the polls, Trump pivoted to acknowledge Tuesday’s midterm elections, which he declared to be crucial.

The party of a sitting president often loses seats during the midterms, he noted. “We gave this a very strong shot,” Trump said.

For weeks, polls have shown Democratic candidates are narrowly ahead of Republican candidates in key races – that includes competitive Senate races in Texas, Alaska, Kansas, Iowa and Maine.

Voters have expressed dissatisfaction with Trump’s handling of his job as president, particularly over the US economy and cost of living.

The prices of gas and groceries have risen since the beginning of the year, and inflation has remained stubbornly high – largely the result of the war with Iran that Trump started at the end of February.